He is an "Ama Lamia" (Vampire Lover), meaning no vampire can make him their servant. Furthermore, vampires who feed on him have their servitude ties with their masters broken, making of him a threat to the vampires' society structure. Later it is revealed that he possesses great spiritual powers which were sealed by his family in order to allow him to live a normal life, as they were too strong for him to control. From their first meeting, he and Hazuki have a tempestuous but affectionate relationship that eventually turns into romance. In the manga, Kouhei's surname is Midou.