Eisen is the younger brother of the current emperor of Kyou. Though he had been eligible to inherit the throne, Eisen gave up his position to become a monk. He is an accomplished musician and is a sweet, thoughtful, timid man. Eisen fell deeply in love with Akane when they first met, and is willing to sacrifice his life for her safety. He is Genbu of Heaven (天の玄武?), one of the Eight Guardians.