|Continuity||OVA (War on Geminar)|
|Voice Actors||Akia Abe (Rea, Japanese)|
Ayumi Tsunematsu (Neizai, Japanese)
Martha Harms (both Rea & Neizai, English)
|Species||Artificial Human (Geminari)|
|Occupation||Agent of the Church (Rea)|
|Relatives||Rea Masaki (sister)
Kenshi Masaki (Nephew)
Rea Second / Neizai One is a member of the Church whose alter ego is Neizai One, a mysterious masked woman working under Ulyte's wing with an unknown agenda.
Neizai was one of three Artificial Humans created by the Senshi Civilization to face and defeat Gaia. It was her purpose to be sent to the other world (Earth) and eventually give birth to a child who could potentially fight and defeat Gaia. Unfortunately, since Rea was accidentally sent to Earth instead, she was the one who had to fight alongside Doll. Because she hadn't been the one meant to fight, she was much weaker than she would have otherwise been, and under-trained. She was 'killed' in the fight, possibly by using a Barrier Reactor without a limiter to try and destroy Gaia, however her Core Crystal survived, and was found by an ancestor of the Mest family, along with the Core Crystal of Gaia. The Core Crystal was eventually implanted in the younger son, Ulyte, allowing him to switch between the two forms.
Neizai One briefly joined Lashara's platoon after the Head Church's headquarters was destroyed by Doll, but she later appeared to show her true colors at the Barrier Workshop while holding a mysterious object in her hands, which was later revealed to be a device that eliminates Core Crystal data.
However she in fact "was" Ulyte, or a part of him. She explained to Kenchi that she was an Artificial human like Doll and had been secretly working against Lord Babalun the entire time. She also explained that due to the Core Crystal put inside Ulyte's body by his father when he was young, his body and personality changed to that of Rea when her awareness became stronger. However, the Core Crystal took its toll on the part that was Ulyte and it finally gave out, forcing the part that was Rea to take over.
It is hinted that she has feelings for Kenshi, although she is more ambiguous about them than the other girls that fall for him.
Her Seikijin is grey with a cape and a mask with active camouflage armed with a large sniper rifle.
- The English version has both her personas having the same voice actress rather than having two different voice actresses like the Japanese version which also gives away the reveal of Rea Second being Neizai One.
- It is heavily suggested that Neizai was one of the three Artifical Humans created to defeat Gaia in the distant past, and was the one whose body was killed in the battle. Was later confirmed by the author in one of his background releases.
- The name Rea the Second might have been an homage to her sister, Rea Masaki, Kenshi's mother.
- Neizai is still a bit angry at Rea for interfering and taking her place as the one to be sent to the other world.