Hida Reiri is the principal and commander of Ataraxia. She becomes the leader of Ataraxia after it became an independent country. She is the daughter of Hida Nayuta, as well as the older sister and semi-secret lover of Hida Kizuna and adopted older sister Hida Setsuna. Carrying the heavy responsibility of protecting her world from the threats brought by the AU Conflict , Reiri was the one who started the Heart Hybrid program.