Tennyo Masaki (柾木 天女, Masaki Tennyo), is a supporting character within the official continuity of the Tenchi Muyo! Ryo-Ohki series.
When she is introduced, Tennyo has white or light lavender colored hair and is a near-exact double for her and Tenchi's mother, Kiyone. Despite her youthful looks, Tennyo is 80 years old, and like her grandfather Katsuhito (Prince Yosho), she often uses an older appearance when among Earthlings. Because of her similarity to their mother, Tennyo would often swap places with her and take care of Tenchi and his friends, Seina Yamada and Kai Masaki when they were younger. She left Earth right after Kiyone died, only to reappear when it came time to introduce Tenchi and his extended family to his fiancee, Noike.
Once she had arrived back on Earth, she was supposed to pretend that she was Kiyone as a part of one of her mother's jokes but admitted who she was when Tenchi, who never knew he had a sister, started crying when he thought his mother had returned. Plus, her father took the joke a bit too far. Tennyo explained her absence by explaining that telling him her age and how some of her old classmates were still around and would have realized that she never got older. Katsuhito later explained to Tenchi that the members of the Masaki family are forbidden to reveal their true identity to the people of the Earth since Earth's civilization is still in the development stage, which is the main reason why Tennyo had to leave.
After introducing Noike to Tenchi and conversing with her brother and grandfather, Tennyo assumed her elderly disguise and left to go on one final trip with her old classmates to Hawaii. She returned from the trip, along with with her grandmother, Airi, just before her father Nobuyuki was to be married to Rea.
In space, Tennyo works in one of Airi's Galaxy Academy production workshop and is a young Philosopher herself. The Tenchi Muyo! GXP novels explains that she designed much of the original Kamidake (Seina's 1st ship).
After the apparent death of Miki Steinbeck, Tennyo meets with Seina and comforts him. Like Tenchi, he initially believed that she was Kiyone and also started crying. He thinks of her both as a sister and a little bit like a mother because of her relationship to Tenchi.
In OVA 4, it is shown she is dating Hakuryo Masaki, who also grew up in the Masaki Village and also ended up joining Airi's workshop. When his elders ask him when he will settle things with her, he says the problem is "timing." This actually means that he rarely sees her without the shared presence of the intimidating Airi. A Doujinshi suggests that she thinks of him more as the "dumb dog she keeps around."
In OVA 5, Tennyo is revealed to be trying to straighten out the mess left behind by her mother and attempting to figure out what she learned about Rea and dimensional travel. Tennyo also has changed her hair color. Her mother's hair was originally also black, which she changed to grey. Tennyo's original color is probably also black but she seemingly changed it too when she was acting as her doppelganger with Tenchi and seemingly got used to it. Maybe now she wants to differentiate her appearance from the one Tenchi recognizes as their mother's. Also, there may be people in the area that remember her and would be stunned to see the exact face of the woman who should be in her 80's or 90's still looking like she was in her 20's.
- The name Tennyo means "celestial maiden, heavenly nymph" (天女).
- A nymph is a minor female nature deity in ancient Greek.
- Tennyo's surname Masaki means "straight grain, spindle tree, (kokuji)" (柾) (masa) and "tree, wood" (木) (ki).
- In OVA 4, Tennyo is the only person who can seemingly get away with calling Airi 'grandmother,' as instead of becoming angry, Airi merely begs her to not do so.
- In OVA 5, episode 4, It misleadingly implies that Tennyo has acquired a large mecha of her own, and uses it to visit Banjo Island. This is Kiriko's mecha, Yomotsuookami. It is unknown if she learned how to pilot it, if it can pilot itself, or if Kiriko or Karen were piloting it and she was hitching a ride.
- Tennyo's Japanese voice actress is Emi Shinohara, who is best known as the voice of Sailor Jupiter/Makoto Kino for the original 1990s adaptation of Sailor Moon