Kizuna Hida

Kizuna was the first person in the world who tested the first Heart Hybrid Gear, his mother owned a research facility (Nayuta Lab) in Ataraxia, so Kizuna was also living in this float when he was small. He was chased out from the research facility seven years ago and was forced to move into Tōkyō float, after his mother encountered Chidorigafuchi Aine, whose aptitude for the Heart Hybrid Gear was found to be far above his.

Though it was only for a short time, he lived with his big sister in an apartment in the Tokyo Float, though she eventually moved to Ataraxia and became the commander there.

Kizuna was called there after Reiri and Kei discovered papers left behind by his mother detailing the method of Heart Hybrid, and its ability to solve the single largest problem of Heart Hybrid Gear pilots; their high magical power consumption and slow recovery rate.

Kizuna has the power to level up a girl through perverted or lewd acts. Kizuna possesses the Heart Hybrid Gear ability, but it is not strong enough to make him particularly important (individually).

Has performed climax hybrid with his sister, though she masked herself at the time, leaving him unaware of her identity.