Yosho follows exploits of the titular son of Emperor Azusa—the protagonist of the previous novel. It details Yosho's life starting at the age of twelve when he enrolls in the illustrious Galaxy Academy and falls in love with his female student guide, Airi Magma, while dealing with the complications that come with the tense relations between their respective countries, Jurai and Airai. Later on, Yosho arrives to defend Jurai from a vicious attack by the space pirate Ryoko, only to make a decision that will have far-reaching repercussions.
A few days after Azusa, Funaho, and Misaki return to Jurai, Sasami, along with Ryo-Ohki, spend the afternoon cleaning the Masaki shrine, as Sasami is still in her "hyper housework mode" from earlier. Suddenly, Washu—secretly observing doodlebugs constructing a nest under the shrine— suddenly greets Sasami and startles her so much that even Katsuhito comes over to investigate the noise.
Noticing Sasami had been sighing, Washu asks her what's wrong, and she deduces that she's homesick since she had hardly seen her parents apart from the past few days they were here. Washu hugs Sasami, and once she's back to her cheery self, she brings up how Ayeka looks a lot more like her mother Misaki than she first imagined. To that end, she rips open spacetime to bring Ayeka to the shrine engulfed in a giant black blob. The blob releases Ayeka, but Sasami is surprised when she finds her big sister's hair looks exactly like their mother Misaki's. As Ayeka looks at herself in a pocket mirror, she finds that her hair reverted to its natural bluish-green color and is "spiky like a pineapple".
Ayeka—now resembling Misaki—realizes that Sasami is overcome with her longing for her mother, and she happily hugs Sasami. Meanwhile, Katsuhito asks Washu how she knew about Ayeka's hair. She explains that during the physical examination she performed on her (along with Zero Ryoko's), she noticed that her phenotype should more closely resemble Misaki's. Now, Katsuhito admits that when Ayeka was four-years-old, she underwent genetic testing. Indeed, seeing Ayeka's natural hair reminds him of old memories of the distant past, back when he was still known as "Yosho". . . .
In one corner of planet Jurai's capital, the enormous tree Tenju, four-year-old Ayeka (whose appearance bears a resemblance to her future sister Sasami) climbs through the window and enters the room of her twelve-year-old brother Yosho. After promising not to climb Tenju anymore out of Yosho's concern for her safety, she tells him that she was eavesdropping on their mothers Funaho and Misaki, and learned that they are going to marry. Indeed, two weeks later, their engagement is confirmed at a session of the Supreme Council.
As is told, even after Funaho gave birth to Yosho, there was still some criticism toward her because of her upbringing (she was an Earthling brought to Jurai by Azusa), much of it coming from House Amaki. Thus, Yosho felt a need to protect and be with his mother, and he even named his First Generation Tree after her.
One day, Lady Seto Kamiki—one of the most powerful individuals in the Imperial Family and one of Funaho's few allies, speaks with her and Misaki—her daughter—about engaging Yosho and Ayeka. Seto also tells Misaki (who openly loves Yosho as a sort of little brother) to stop visiting Yosho's room through the window to wake him up, as well as to stop calling him "Yosho-chan" because it's embarrassing for a soon-to-be adult.
Later, Yosho is visited by Misaki, though he can't see her, and in addition to calling him "Yosho-dono", she says she can't wake him up anymore. After she leaves, Ayeka enters his room through the front door, but her hair changed from blue to purple. He realizes that Ayeka edited her genes to look more like Funaho because he sees his mother as the ideal woman. Yosho tells Ayeka that she looks nice, but hides an inner pain in his heart in doing so. In truth, while Yosho doesn't hate Ayeka, he instead has an unrequited love for Misaki, and the fact that she no longer warmly greets him every morning drives him to tears.
A few days later, Seto invites herself into Yosho's room bearing tea and persimmons (grown from the seeds of the very same fruits Funaho offered to Azusa on Earth). To his surprise, Seto wants to enroll him into the Galaxy Academy as part of this year's exchange program, even as it had already departed last month. Yosho eventually realizes that Seto is giving him the opportunity to distance him from Misaki, and he accepts her proposal.
The Supreme Council decrees that Yosho and Ayeka's marriage will happen in two years after Yosho returns from his studies abroad. From then on until the day he left Jurai, Ayeka and even Misaki would burst into tears whenever they visited him, while Funaho subtly tells her son to use his time away from Jurai to find closure with his feelings for Misaki.
Embarking on his ship Funaho, Yosho arrives at the Galaxy Academy, a massive institution the size of a solar system. He is given no reception when he lands, but he finds not being treated like royalty anymore a refreshing change of pace.
Instead, the only person to greet him is his volunteer student guide, a fifteen-year-old girl named Airi Magma. She finds Yosho interesting for how emotionally mature he is for a twelve-year-old, especially compared to the other special transfer students who are usually bratty. Airi is somewhat disappointed that she won't need to "straighten out" Yosho, which makes him feel a certain affinity toward her since she reminds him of Seto. Airi tells Yosho "what you create here will undoubtedly be all your own", and with that, she leads him into the academy.
Later that night, Yosho is confused at how the huge welcoming party in town she brought him to was supposed to be "private and informal". Airi explains that there are people from everywhere in the galaxy who come here with things to celebrate, and there's always some party happening every night. She then puts a hat with a mark on Yosho's head, and suddenly starts getting warm greetings from several people. The crowd goes silent when Yosho lets slip that he's the Crown Prince of Jurai, but it quickly resumes, albeit Yosho starts getting hugged and kissed by a bunch of older, drunken women. Airi and Yosho leave once curfew is announced, with Airi joking that Yosho is popular with women. She tells him she's already registered him for his dorm room and bids him a good night before parting ways with him.
Just when he's alone, Yosho's senses tell him that he's being surrounded. He feigns obliviousness and tricks his attackers into striking. He notes that they're Juraians like him, but their combat skills are no match for his, and the fight ends as soon as it begins. It turns out that they were five older boys, but there was another group watching Yosho. They now reveal themselves and carry away the other boys while their leader introduces himself to Yosho as Kanemitsu Hirata. He tells him that the boys that attacked him were sent by "idiots" who don't understand that their royal status means nothing in the academy. He also warns him to get another guide than Airi, but a nearby curfew monitor forces him to leave before he can elaborate.
Yosho arrives at his room and thinks about what Kanemitsu said about Airi, figuring that it must be related to the strange reaction he got when he revealed his royal status. He does some research on Airi through the Academy personnel data banks and discovers that not only is she from the planet Airai, but she's the daughter Gaira Magma, the leader of the Head temple of Airain—the planet's religion.
As Yosho recalls, Airain is the largest religion in the galaxy. It managed to spread via the discovery of mysterious relics on several planets that indigenous people created religions around. It was only thousands of years later that a Galaxy Academy research team led by Washu discovered that all these relics originally came from Airai, and this made Airain much more popular. However, Airain never took influence on Jurai, mostly because the people already worshipped Tsunami and her Royal Trees and refused to accept other gods. Thus, the people of Airai are hostile to the "heathen" Juraians, and Yosho realizes that Kanemitsu was worried he would be "taken in" by Airai. Yosho doesn't believe that Airi has any malicious intentions, though he wonders why she specifically chose to be his guide.
The next morning, Airi energetically wakes Yosho up over the communications monitor, telling him to get dressed and meet her at the nearby park. There, Airi, who certainly found out Yosho was researching who she was, asks if he still wants her to be his guide. Yosho says she does, saying that it's good for Jurai's future that he foster relations with other countries. With that, they take care of Yosho's paperwork and have breakfast before departing again. However, Yosho has a strange feeling, as though things have been out of place since he met Airi. Needing answers to his questions about those that attacked him, he calls Airi at night and gets her to meet him at a specific time and place, though the embarrassed tone he says it in makes him believe she probably thought he was asking her out on a date.
To shake anyone who might be tracking them, Yosho and Airi go on a "date" and go to various places, but Airi drags Yosho along at a breakneck pace to get everything done in a single day. Eventually, she tires, and they rest at the park where they met earlier. Out of the blue, Airi asks Yosho if she thinks of her as an "old lady" because she's three years older than him, but when Yosho calmly says he doesn't, Airi starts playfully wrestling with him to get him to act his age and be more expressive!
Airi eventually relents and invites Yosho to have dinner with her. She takes him to a restaurant named "Narsis", inside a mall near the park. While initially unassuming, Yosho discovers that the restaurant's terrace has a majestic view. As his guide map only says "secret", Yosho asks if they're in a restricted area, but Airi says it's simply one of many places meant to surprise newcomers. This place, for instance, was a crater created when one of Professor Washu's experiments went haywire, and the students under her campaigned to preserve the site, named "Washu's Pore", as one of the few examples of her making a mistake. Soon enough, they're served dinner and Yosho finds the food to be better and homier than what was served at the dorms. Yosho and Airi continue to chat about various topics until they finished eating, with Airi insisting on paying the bill because she thinks Yosho shouldn't frivolously spend money he got from his parents; meanwhile, she works a part-time job tutoring elementary school students. Nonetheless, Yosho and Airi part ways at the streetcar station, but Yosho is soon met by an old man named Kaneaki Hirata, the butler to a certain Amaki Kasen that has been ordered to bring Yosho to his master. Despite knowing he could take down Kaneaki and the ten other henchmen backing him up, Yosho accepts the offer and enters a landcar.
Along the way, Kaneaki clarifies to Yosho that he is the father of Kanemitsu, the man Yosho met the other day. Arriving at their destination, they're greeted by Kasen, a sturdily build seventeen-year-old, and the student that Airi served as a guide to before Yosho. However, Yosho already knows that Kasen wants Yosho to pick another guide than Airi, but tells him that he refuses. Angrily, Kasen says that he, the Crown Prince of Jurai, is being put on the leash of the daughter of a hostile foreign leader and that it's a national disgrace. He additionally suggests the possibility of him "turning" on Jurai and giving Airai a First-Generation royal tree, and he even warns of the First Empress, Funaho, being put in a difficult position. However, none of Kasen's claims changes Yosho's mind, and he states his intention to abide by the rules of the Academy and its neutrality in foreign affairs.
Kasen relents and allows Yosho to leave, and once he returns home, he accesses his ship Funaho in orbit. He gets Funaho to contact Mikagami, Lady Seto's ship, as Seto has superior information gathering and analysis abilities, and he uses the ship to analyze the data he gathered today, discovering that several intelligence organizations had marked them. He then tries to find more information on those who would present the most danger to Airi, namely Kasen and his minions, but strangely enough, there's no available information on the students. Yosho realizes that Seto knew he would try to access the information and got rid of it, probably wanting him to do all the important work himself. He also discovers that the six Juraians who came to study at the academy last year happen to be Kanemitsu and the five men that were with him that night and that they're trying to protect Airi in their own way.
The next day, Yosho makes his way to a cafeteria to have lunch with Airi but is first confronted by Kanemitsu, who compliments him on his handling of Kasen. Nonetheless, he warns Yosho that things will only get worse if he stays by Airi's side. As he says, Kasen is related to House Amaki, one of Jurai's four great families. Yosho realizes that Kasen is specifically in contact with Shuzan Amaki, whose thirst for power drives him to continually plot against House Masaki; that said, this was different than his typical scheming. Soon enough, however, Kanemitsu leaves when Airi greets them (as Airi notes that he has trouble with talking to girls), and she and Yosho have lunch.
The next few days for Yosho and Airi go by without any incident, but one day, Yosho receives an anonymous e-mail that warns that said his interactions with Airi "were not desirable". He rushes over to Airi, who says she received the same e-mail, but she says she often receives this kind of harassment and has the Guardian System, Kaunack, to protect her. Yosho knows the GS won't be enough to protect Airi against a skilled Juraian fighter, but Airi interrupts his thoughts and tells him to not take things so seriously. She even sheds a tear out of pity for the mature world he lives in, only to suddenly wrestle with him again like on their date. Once she's finished, Yosho holds out a wooden ring to give to Airi. He explains it's a good luck charm and he wants her to have it. Airi refuses the gift, saying it's too valuable to give away, but Yosho insists, saying she's taken such good care of him. Airi accepts the ring and even gets Yosho to say it looks good on her.
A few more days pass with more harmless e-mails, but one night, a panicked Airi bangs on Yosho's door speaking about something that had happened to her. He takes her to the counseling room to calm down, and she explains that as she was walking alone through the park her GS system suddenly activated and battled an invisible enemy. Before she could have time to boost the power of her GS, the assailant warns her to stay away from Yosho, threatening her with a sword. Just then, a voice rang in her head saying it'll protect her, and another GS appeared and beat back the attacker.
Airi asks Yosho if he knows anything about what had happened, suspecting it had something to do with the ring he gave her. She's also very curious about the voice she heard. Yosho doesn't want to tell Airi about Funaho, but when he tries telling Airi that it's getting late, she refuses to leave him, so he decides to take her to his ship.
Evading curfew watch, Yosho and Airi meet at the spaceport where Funaho is docked. They board the ship and enter the bridge, but Airi is disappointed to learn that the voice in her head that she heard earlier was simply the ship's computer and not one of the Royal Trees. Yosho laughs as Airi is unaware of the true nature of his ship, and Funaho transports both of them to the real main bridge, the hall of the royal tree. They find themselves in an outdoors setting in front of the tree Funaho itself. Yosho introduces Airi to Funaho, but Airi suddenly gets on her knees and desperately asks the tree what it is and what it knows about the "Three Goddesses". Funaho doesn't answer, and Yosho has to hold back Airi, who is breathing heavily and distressed.
Yosho leads Airi to rest on a nearby bench and asks what she was trying to ask Funaho. As she says, her research at the Academy led her to discover that there have been a scarce twenty-eight encounters of intelligent beings from higher dimensions. However, there also seemed to be three particular goddesses that are much more powerful than the rest, and Yosho realizes Airi is talking about the Light Hawk Wings, which are the manifestations of the Three Goddesses.
Airi continues and tells Yosho about the Airain religion. Her great-grandfather was responsible for making Airain the galaxy's most powerful religion, but to maintain such a large religion, having a unifying icon was important. The Airain council first attempted to have Airi's grandfather and then father replace her grand-grandfather as the religion's figurehead, but eventually, this was no longer a viable option. Instead, the council wanted a new god, but when it was clear they couldn't deify her great-grandfather because he didn't have absolute power, they wanted to turn Tsunami into their new god.
Airi confesses that she used to believe in the Airain dogma and that Jurai was monopolizing Tsunami, but spending time with different cultures in the Galaxy Academy taught her that she'd been lied to, and the council was even going against their own teachings. Thus, instead of claiming Tsunami from Jurai, Airi was hoping that another one of the goddesses would work for the Airain faith.
Yosho comforts Airi as she breaks into tears, but he tells her that Tsunami isn't a god, at least not the kind she was looking for. He also tells her that Funaho's silence doesn't mean it forsook her, but that it just scared her with her sudden questioning. To that end, Airi tells Funaho that she's fine, and the tree surrounds Airi with beautiful lights.
Sometime later, Airi wakes up Yosho, and, seeing as it's already morning, they decide to eat breakfast after Airi takes a shower. Yosho leads Airi into Funaho's residential area inside subspace where a holographic lady-in-waiting shows her to the guest bathroom. Later, she meets Yosho again wearing Juraian clothes and having her hair down, which mesmerizes Yosho. However, what interests Airi is the fine quality of the Juraian silk—the very best quality silk there was—her clothes are made of. Yosho tells Airi to keep the dress and that he has plenty more to share, and Airi agrees to purchase more silk at what he believes is a fair market price (even though he could've just given it away for free).
Kasen Amaki fled back to Jurai after only three months of study, and his minions joined up with Kanemitsu's group and focused on their studies. Finally, the days were peaceful, and Airi and Yosho were no longer harassed. That said, Yosho still believed there was something he overlooked in the "homework" Seto had given him about the whole affair, but by now that was swept into a corner of his mind by his fun campus life with Airi. Before he knew it, six months had passed.
One day, he greets Airi again, but she seemed off. Of course, Yosho already knew what this was about. He had received a communication from Lady Seto last night, where she told him that his father Azusa has ordered him back to Jurai to fulfill his duties as Crown Prince for six months out of the year. To Airi's relief, Yosho tells her that he'll return to the academy in six months.
The day before his departure, Yosho can't find Airi anywhere to give his goodbyes, but he went to see Kanemitsu in his dorm. Apart from giving his formal goodbye, Yosho also asks Kanemitsu to do a favor for him and look after Airi while he's gone, but he claims that he'll also be returning to Jurai in a few days. Yosho knows Kanemitsu is acting strange, but Kanemitsu suddenly attacks him with his sword, which he blocks with a button on his uniform. Yosho suddenly realizes that Kanemitsu was the person that attacked Airi, only to be defeated by Funaho's Guardian System. Kanemitsu admits that much, saying that his father Kaneaki serves Kasen and House Amaki, after all. However, he was just informed that because he failed to separate Yosho and Airi, he's no longer of use and is being recalled from the academy, free to do whatever he wants. Yosho says he could've asked Lady Seto to protect him and his father from blackmail by House Amaki, but Kanemitsu insists that they haven't sunk so low, his father isn't being blackmailed, and now. Yosho asks Kanemitsu why House Amaki wanted to try and separate them, but he says he doesn't know. That said, his father told him to watch for others and make sure Airi isn't harassed.
They proceed to casually talk about Lady Seto and Utsusumi until they realize how much time has passed. Yosho shakes hands with Kanemitsu, transferring his invisible guardian to him, just in case, and once he leaves, he realizes there was still one place he hadn't looked for Airi in. He boards Funaho and finds her in the hall of royal trees enjoying herself with holographic puppies created by Funaho and he joins in on the fun. At one point, Yosho and Airi touch skin-to-skin, a feeling that Airi swears to remember until Yosho returns from Jurai.
Once again, they wake the next morning after falling asleep and proceed to have breakfast in Yosho's living quarters.
One week has passed since Yosho returned to Jurai. He realizes that his senses have been dulled over time, though he's completely gotten over his love for Misaki—in fact, he oftentimes forgot about her entirely. Speaking of Misaki, she wakes him one morning to meet with Seto and Utsusumi at the Jurai Imperial Academy.
There, Seto and Utsutsumi get into a back-and-forth over whether he should take Yosho to introduce him to the campus faculty, or if she should bring him and Misaki along on some errands. Suddenly, Seto brings up how this was the spot where Utsutsumi "molested" her one time, but Utsutsumi says that he was looking for her when he tripped and fell on her while she was sleeping, accidentally touching her breasts. As a nine-year-old boy at the time, Utsutsumi didn't understand that Seto was joking when she told him she couldn't get married anymore and that he needed to "take responsibility" for his actions, and 130 years later, he built up the courage to do so and proposed to her. Seto tells Yosho that Utsutsumi tried to take him because he didn't want her to tell him about the embarrassing story they just recounted. With that, Seto leads Yosho and Misaki on their errand, and Yosho better understands why everyone—even his father—fears Seto.
The three of them enter the Academy and meet with its principal, who says he summoned the person Seto was looking for. It turns out to be Kanemitsu—now a student at the Academy— whom the principal makes sit down a little ways away from Misaki since he and Yosho know she tends to suddenly glom on anyone she finds cute. Kanemitsu thinks he's going to get punished for working for Kasen Amaki, but it turns out Seto is offering to let him return to the Galaxy Academy. However, Kanemitsu says that while it's his dream to be a student there, he wants to earn it himself. Undeterred, Seto offers to make a wager with Kanemitsu. If he can stay on top of his class when doing his exams, she'll pay for all his expenses and pay bonuses for other exams that'll fund his education for as long as he stays there; then, when he's finished, he can start working for her and Misaki—something he's always wanted to do. Kanemitsu happily accepts the offer, but when does Seto customarily gives him a lock of her hair as a good luck charm, Misaki one-ups her mother and cuts off an entire third of her hair to give to Kanemitsu, but he passes out from nervousness.
Kanemitsu leaves, and it is only then that the principal brings up how, hopefully, he never learns that Seto had covertly shelved Kanemitsu's chance to get a scholarship at the Galaxy Academy, which would've paid for all his expenses regardless. Yosho remembers what a pirate leader once said: "There was a god and a demon on Jurai." With the sudden revelation about Seto's scheme, it's not too hard to figure out what demon they were talking about.
After six months of performing public duties on Jurai, Yosho returns to the Galaxy Academy and is greeted by Airi. She goes onto Funaho and lovingly plays with holographic puppies, but after Yosho leaves her alone, she confides to Funaho that Yosho has reverted to how she met him.
Indeed, for as much as Airi wants Yosho to loosen up and laugh wholeheartedly, she couldn't do so even after several years. Every time Yosho departed for Jurai six months out of the year, he would return to the Academy having reverted to his old, overly-mature self.
One month after Yosho again departs for Jurai, Airi receives a message from her father, Gaira, whom Airi is worried has lost weight again and is in poor health. Gaira simply says "I'm sorry", indicating that he is no longer able to protect Airi from the Airain council, who disapprove of her defying their religious doctrine and staying at the Academy. Then, Gorba, the highest-ranking member of the Airain council, appeasr and orders Airi to return to Airai within two months, even though Airi will get her diploma in six months and Yosho would return in five. Airi tries to reason with Gorba to no avail, as he has arranged for Airi to be married and will no longer tolerate her insolence.
The transmission ends and Airi knows that she must accept Gorba's demands, knowing that she can't abandon Airai and her father. However, she wishes she could see Yosho again. She cared about him like a brother, and could not bear to never see him again. First, she tries to become a guide to Lady Seto, who is coming to visit the Academy, but she is repeatedly turned down because of the poor diplomatic relations between Jurai and Airai. Undeterred, Airi seeks out Kanemitsu, who has faint ties with Seto. However, every time Airi catches up to him, Kanemitsu insists that he isn't close enough to Seto to make any personal requests on her behalf and eventually escapes her clutches.
A dejected Airi finds herself in her room watching Seto's welcoming reception on TV, but she realizes she has a chance to meet her. Seto was going to visit one of the facilities of the philosophy department, and Airi happens to be friends with the philosopher who worked there and thus had a pass to private passageways. While Seto takes her tour of the facility, Airi manages to sneak inside and evade security, and finally meets Seto—right when she only has a few bodyguards and the philosopher with her—wearing Juraian clothing. She introduces herself as the one who served as Yosho's guide and tries talking to Seto, but she's paralyzed by the gaze Seto gives her. Unfortunately, she tells Airi that it wouldn't be prudent to talk to her—the daughter of Airai's head of state— in public like this, and she and her group quickly excuse themselves.
Embarrassed, mortified, and sobbing at the thought of never seeing Yosho again, Airi flees the facility. However, Seto and the philosopher lightheartedly discuss what happened, with the latter joking that Airi is rather inexperienced to try and fight her over Yosho. They then talk about Washu and Naja, two former philosophers that the old philosopher used to work under, and how they constantly toyed with him and others and would always catch them when they tried to escape. Unfortunately, Naja has since died, and Washu is missing. As he says, the Galaxy Academy has gotten bigger, but also lonelier.
Seto and Airi
Distraught over her failed attempt to speak with Seto, Airi ignores the nightly celebrations and goes right back to her room, only to realize she's hungry. To her shock, however, Seto suddenly knocks on her door with baskets of food served at "Narsis"; it becomes abundantly clear to Airi that Seto was simply teasing her earlier at the philosopher's facility.
As Airi learns, Seto actually cooked the food at the "Narsis". herself. She tells Airi that she should learn how to cook herself since she apparently has a keen sense of taste and tells her "If you can make good food, you can survive anywhere." She continues and describes how she's taught other people to cook with varying degrees of success: Misaki knows the basics but is more interested in eating than cooking, Funaho is too good of a cook that can't be taught anything more, and Ayeka is "curiously clumsy" and prefers sewing. She hopes that if she has another granddaughter, she'll teach her everything.
Airi and Seto enjoy dinner followed up by tea and dessert, all of which Airi finds delicious. When they finish, Seto tells Airi that Yosho's mother, Funaho, is thankful that Yosho acts his age when he returns to Jurai instead of being under stress. Conversely, Airi says that she was shocked at how Yosho had reverted back to his "severe expression" when he returned to Jurai. She asks Seto if she could let Yosho stay at the Academy permanently, or at least until he grows up more since she wants him to have childhood memories.
Seto bluntly asks Airi if she loves Yosho. Airi knows the answer, but she can't bear to say it in front of her. Instead, she gets frustrated with Seto for making her have to face reality by asking her such a question; Airi, of course, will have to return to Airai in a month to get married and never see Yosho again. However, Seto—grief in her expression—tells her that members of House Masaki have always had difficult romances and end up being sacrificed for Jurai's sake: Yosho's grandmother (Amame, who left the Imperial Family to marry his grandfather), her brother (who took the blame for a pirate attack and exiled himself to protect Mitsuki Amaki) are just a couple examples. That said, she goes on to say that she loves Yosho's father, Azusa—perhaps even more than her husband—because of how she brought him to Jurai, has looked after him since, and loves everything that he loves. It's for that reason that Seto sees Yosho as her son, but while a part of her doesn't want him to leave Jurai, another part of her does, if he chooses to do so as Amame did.
Airi feels confused as to what Seto is trying to say, but Seto continues speaking and brings up the power of Jurai's Royal trees, which could easily destroy an entire country. She reveals to Airi that she believes her marriage is part of a greater scheme perpetrated by the Airain council to get control of these trees.
As she explains, Kasen Amaki—the student to whom Airi was a guide before Yosho—was adopted into House Amaki when he was an orphan, but nobody knows who his real parents are. However, Seto is certain that Kasen is secretly a member of the Lufins, an Airai family related to the Magmas. Thus, the scheme is for Kasen to marry a daughter of House Amaki, and for Airi to marry a member of the Lufins, thereby making the Magmas and House Amaki distant relatives through the Lufins. From there, House Amaki could eventually put one of their own on the Emperor's throne and give control of Tsunami—the greatest of all Jurai's trees—to the Magmas.
Seto is determined to expose Kasen and crush his marriage, but she can nothing about Airi's arranged marriage. Seto informs her that Yosho will be returning to the Academy in two weeks to file paperwork for his leave of absence, which gives Airi a final chance to see Yosho. She knew she didn't have what it took to defect from Airai, but she could at least say her final goodbyes. Seto needs to leave and tells Airi that she needs to make a decision... and that it's not too late to start training as a cook.
Two weeks later, Yosho returns to the Academy, and he and Airi go into Funaho's bridge to get swarmed by puppies as usual. They then go eat lunch inside Airi's room within Funaho's living quarters, only to have more fun with the puppies. Eventually, dusk comes, and they sit on a hill to watch the sunset. Once the sun sets, Airi begins sobbing, both of them knowing that this was the last time they would see each other.
Finally, Airi declares her love for Yosho and they share a kiss, and then, "the only sounds were of their breath and the rustling of grass".
When Airi returns home to Airai, Seto reveals Kasen's origins and causes his marriage to Shuzan Amaki's daughter to be canceled. However, Airi finds out that she would be marrying Gorba himself; Seto had foiled the Airain council's plot and prevented them from marrying Airi to a member of the Lufins. Then, in what they call a "religious ceremony", planet Airai transfers its political center to a satellite city and closes itself off to the rest of the world, supposedly only for a few years; of course, this is to prevent anyone from knowing what was happening on Airai.
Yosho is driven by impulse to see Airi, as he could not find out anything about her and Seto would say nothing about it. However, he was aware of the consequences of doing so and does nothing. Unfortunately, Yosho and Airi's feelings would go unrequited for the time being. And so, five years passed...
Planet Jurai is attacked for the first time in two thousand years by Ryo-Ohki, or "Black Destruction" as it's known. It comes at the worst possible time, as the Emperor and most of the Imperial Family are taking tours abroad, and their powerful first and second-generation Tree Ships aren't around. Yosho, however, is returning from his duties and orders Funaho to full speed back to Jurai.
Tatsua Masaki, the acting commander of Jurai's defense forces, musters a squadron of third and fourth-generation ships and engages Ryo-Ohki, but Ryo-Ohki emits a high-pitched Meow! that scares the third-generation ships so much that they involuntarily lower they defenses, and Tatsua and his force are obliterated.
As Ryo-Ohki strikes Tenju, Ayeka emerges from her room and takes to her second-generation ship Ryu-Oh, despite only recently making her connection to her ship and whose outer hull isn't even finished yet. Ryu-Oh engages Ryo-Ohki, but Ayeka isn't properly synchronized with her ship and can't use its full power. Ryoko then targets Ayeka's favorite garden on Tenju, and this enrages Ayeka so much that she overloads Ryu-Oh's power systems when she tries attacking again and causes it to shoot out energy wildly, ironically hitting and destroying the branch the garden is located on.
Leaving Ryu-Oh to Ryo-Ohki, Ryoko disembarks on Tenju, where she battles warriors with an evil spirit of hers. Meanwhile, unaware of the nearby fighting, Ayeka's younger sister Sasami lets herself into the hall of the second-generation trees, enchanted by the magical sight and melody. However, one of the ships defending Tenju on the outside is hit by Ryo-Ohki and collides with Tenju's trunk with a massive explosion. This shock makes Sasami lose her balance and fell into an abyss...
A hit from Ryo-Ohki cripples Ryu-Oh, but just as Ryo-Ohki attacks again, Funaho arrives and protects Ayeka with Light Hawk Wings, driving Ryo-Ohki away. Yosho learns that Ryoko is inside Tenju and disembarks from Funaho, leaving it to battle Ryo-Ohki.
Ryoko defeats the last of the guards and attempts to break into the hall of the royal trees, but her attacks fail to damage the door leading to the hall and she suddenly experiences unbearable pain. At the same time, at the very bottom of the hall, Sasami had died instantly from her fall, but her blood spilled out and touched the water of the pool of a small tree— Tsunami's tree. Sasami dissolves in a whirlpool as she and Tsunami assimilate into each other and create a brand new entity. Ryoko communicates with Tsunami as this happens and falls into a trance. Yosho confronts Ryoko, who unconsciously battles him before getting blown out of Tenju in an explosion of their energies. Ryoko regains consciousness and communicates to Kagato through her three gems that she is unable to capture Tsunami.
Ryo-Ohki collects Ryoko as she flees, and just as Ayeka races inside Tenju to meet her brother, Yosho says that he will capture Ryoko—unaware that this would be their last conversation for a long time. He transports back to Funaho and tells Tatsua, who survived his earlier battle with Ryoko, that he will be assuming command on Jurai, taking all responsibility for what will happen from then on; this is done to force the ever-scheming Shuzan Amaki to place the blame for the attack solely on Yosho and no one else. Of course, Yosho also had Ayeka to consider. Even after some years, Ayeka still loved him and wanted to marry him, but this hurt Yosho, knowing that his heart already belonged to Airi and Ayeka would only ever be his little sister. So by accepting a possibly fatal battle with Ryoko in space, Yosho feels a sense of liberation.
As Yosho continues his pursuit of Ryoko, he realizes they're coming up upon an asteroid belt with a hyperspace transporting device that delivers the mineral-rich rocks Jurai. Yosho comes up with an ingenious plan: by using Funaho's great power, he could transport both himself and Ryoko faraway and destroy the transporter in the process, essentially covering his tracks as he escapes from Jurai permanently. He chooses to go to Earth, where his mother was born, as she'd told him stories about it and was excited to see it himself.
Meanwhile, Ryoko thinks about what she's going to say to Kagato about her failure to capture Tsunami. While she had always been a tool to her master, Ryoko had recently started to develop a sense of self. As her emotions develop, she finds following Kagato's orders to be a waste of time and only finds pleasure in destruction. She realizes that Yosho is guiding her near the asteroid transporter and communicates with him, accepting his proposal for battle. Funaho and Ryo-Ohki enter through the transporter—which explodes in the process—and are teleported to Earth's solar system.
Ryoko suddenly teleports to Funaho's bridge and tries to attack Yosho, but Funaho transports Ryoko to its sub-dimensional area so they can battle in earnest. Though he is a skilled fighter, Ryoko has more raw power than him and can't be harmed. Thus, he summons his Light Hawk Wings and causes Ryoko to panic, since she was unaware individuals could generate them as opposed to ships. He channels his Light Hawk Wings into a sword and severs two of Ryoko's three gems, but she manages to teleport back to Ryo-Ohki.
Funaho battles Ryo-Ohki, but to Yosho's shock, Ryo-Ohki's attacks are passing through the defenses of the Light Hawk Wings. As they neared Earth, a badly-damaged Ryo-Ohki rushes forward to ram Funaho, but Yosho uses Funaho to steer both ships toward Japan, prepared to die in his mother's homeland.
Yosho experiences a dream of being comforted by Airi, but he wakes up in a room next to a girl he'd never seen before. She leaves to fetch water when he wakes up but an old man enters to greet him. His name is Tairoh, but he laughs when Yosho introduces himself since it so happens that a nearby mountain actually shares his name. However, their conversation is interrupted by a scream from outside. Yosho gets up to find the girl, Kasumi, being strangled by an injured Ryoko. She demands that Yosho give her back the two gems he took from her because she is unable to control her hands.
Suddenly a bright light emerges from Kasumi's bosom and knocks back Ryoko. Yosho rushes forward and stabs Ryoko in the neck with his Master Key, seizing the final gem. Ryoko tries fighting back but is defeated and collapses after a minute of intense fighting. Yosho discovers that the power from within Kasumi came from a wooden comb she was carrying, a memento from her mother. As it turns out, Kasumi's mother was Funaho's younger sister, and this was the same comb—originally belonging to Azusa—Funaho gave her as a parting gift all those years ago.
"Those born into the Masaki House shared a destiny. They would always wander and face change."
Once Yosho disappears without any trace, the Juraian Imperial Family conducts a conference call through their royal trees. There, Shuzan Amaki is more than eager to put all of the blame for the attack by "mere pirates" on House Masaki, and he quarrels with Tatsua Masaki over the details in the report of what happened. Misaki is about to rant at Shuzan, but Lady Seto is the one who sets Shuzan straight, sarcastically reminding him of how his ship's communications were somehow "jammed" despite being closer to Jurai than Yosho was. Shuzan relents and agrees to not blame House Masaki for anything in exchange for not being suspected of deliberately delaying his arrival to Jurai.
Once the official meeting ends, Azusa, Funaho, Misaki, and Seto via channel have a meeting of their own aboard Kirito. They discuss the findings in Tatsua's report—believing that Ryo-Ohki's power surpassed that of even a first-generation Royal Tree— as well as Ryoko and Kagato, as Seto had been studying them for some time. As she says, Ryoko had been infamous in other star systems for seizing artifacts and information from ruins of pre-historic civilizations, and as for Kagato, nothing was known about him before he became a wanted criminal 5000 years ago. In one incident Kagato had annihilated an entire group of poachers who were on a planet designated as a conservation reserve, but more interestingly, Seto reveals that one of the people on that planet performing conservation research was none other than Washu Hakubi, an eccentric scientist and founder of the Galaxy Science Academy.
Kagato was Washu's assistant, proven by two photos of them together that Seto shows, though Kagato puzzlingly appears as a woman. Seto explains that the woman in one of the photos is actually Washu's friend Naja Akara, whom Kagato is a clone of. The real Naja died 5000 years ago during a pirate attack on an archeological excavation on the planet K1190. This was the same planet that Seto herself was adopted by her father, Ushio Kamiki, when she was six years old, as she was an orphan of some treasures hunters that were killed.
As for Washu, she was found 20,000 years ago as an orphan on the Juraian-controlled planet Kanemitsu when she was about three years old. She had no recollection of her past, but she did have three red gems on her, the same ones that give power to Ryoko and Ryo-Ohki. Seto says that Kagato is using something that Washu developed for his own purposes, but if other countries find out what happened on Jurai, they will seek to acquire it themselves. To prevent knowledge of the gems falling into the wrong hands, they organize efforts to seek out Yosho and/or Ryoko, but even as they sent an investigation team to Earth, Funaho managed to keep things concealed and forced the team to return empty-handed.
Six years pass, and there has still been no information about Yosho or Ryoko, leading some to believe they killed each other. The marriage between Yosho and Ayeka was forced to be annulled and the heads of the Houses were planning to marry her to someone else, but Ayeka still had feelings for her older brother; in fact, they grew even stronger as her ideals of Yosho during his absence. The day before her arranged marriage partner would be announced, Ayeka decides to leave Jurai to find Yosho. While she can't find Yosho herself, she can always refer to the experts still looking for him, whose information Ryu-Oh can freely access without being noticed. She successfully sneaks away aboard her ship and enters hibernation to leave the ship in the hands of her two guardians, Azaka and Kamidake. Not only is she unaware that she'll be asleep for 700 years, but Sasami had also snuck aboard out of concern for her sister, and that it was Tsunami's power that bested Juraian surveillance and allowed Ayeka's amateur plan to succeed.
Predictably, the sudden disappearance of both Ayeka and Sasami causes an uproar. Seto is distraught at how her surveillance systems were somehow bested, but the real trouble was for Yosho's mother, Funaho, who was taking increasing criticism for her son's actions that indirectly caused this to happen. Shuzan Amaki in particular was pestering Funaho about this, but he pushes his luck too far eventually. One day, he bluntly calls Yosho as incompetent as his father for failing to capture Ryoko despite possessing a first-generation ship. Refusing to keep quiet about criticism of her son, Funaho dumps a cup of sake over Shuzan's head, signaling a challenge to a duel (though Misaki suspects Seto had somehow arranged for this to happen).
Unfortunately for Shuzan, who was ecstatic about the duel, Funaho gets drunk, yells "come on you mother#!*@er!", and proceeds to beat him up with a large club. Utsutsumi, who still has a lingering grudge against Funaho for stealing the title of First Empress from Misaki, gets drunk himself and also tries fighting Funaho, only to get clobbered like Shuzan. As Misaki explains, she and Funaho had been training, and Funaho could beat her when using a staff. Utsutsumi and Shuzan keep trying to fight to the detriment of their health and Funaho becomes increasingly berserk in her drunken state, eventually destroying the hall she was fighting in before she sobers up.
On Jurai, where its pirate traditions remain strong, those with great martial prowess are seen with respect. By besting Shuzan and Utsutsumi, Funaho had finally cemented her position as the First Empress, and nobody even challenged her again... nor did anyone ever offer her alcohol again.
A few months have passed since Yosho's battle with Ryoko, and while recovering from his injuries, he decides to live out his life with Kasumi. He takes everything he needs out of Funaho's subspace, as once it fully takes root, it'll slowly lose power and he'll never be able to access it again. As for Ryoko, he'd taken all three gems from her, but she wasn't dead. Seeing an "unexpected beauty and purity in her eyes" that reminds him of Ayeka, Yosho decides to spare Ryoko and seal her up in a nearby cave. Thankfully, Tairoh and Kasumi have no trouble convincing anyone who saw the fierce battle that what had happened was between a warrior and an "ogre".
While Airi never left Yosho's heart, Kasumi had entered his. He marries her a few years later, and they have three children. In the meanwhile, Yosho discovers that Funaho has not been losing any power like it was supposed to after being rooted. He realizes it's because it's been taking power from Ryoko's gems which contain the same type of energy used by the trees and that they're indeed equal to that of a First-Generation Tree. However, the fact that Funaho isn't losing power means that he and his family could use it to extend their lifespans.
Kasumi could not accept the concept of living for such a prolonged period and chooses to die naturally. She lives a long and happy life before passing away at the ripe old age of 138. That said, Yosho decides to pretend that Funaho had lost power and not extend the lives of his descendants any more than they already have been due to inheriting his bio-fortified genetics. Of course, the more descendants Yosho had, the more difficult it would be to keep the secret of his unusually long lifespan. Some tenacious people would try to contact Yosho to get the secret of longevity, but Yosho "would have no mercy" to protect himself and his clan, and eventually, people came to understand not to trifle with Yosho.
A while after Kasumi died, Yosho decides to contact Kanemitsu at the Galaxy Academy through the power of Funaho, knowing full well Seto will pick up on it. The two men make contact, but the moment Kanemitsu utters Yosho's name, Airi butts in. Yosho and Airi are at a loss of words for each other since they've not seen each other in so long and have grown up, but Airi soon calls Yosho an idiot for making her worry. She is about to explode with anger, but is calmed down as she's swallowed up by holographic puppies from the ring Yosho gave her.
As Airi calms down. Yosho sees a girl in the background about the same age as Airi when he'd met her. To his shock, this girl introduces herself as his daughter, Minaho!
Yosho has no idea what had happened in the more than a hundred years that had passed since he was a student at the Academy, but he was sure that those "difficult but fun and boisterous days" would return.