西崎 秋斗

The protagonist who is attending Ryuusei Academy. An unfortunate person who got wounded by a Youma, which infected him with a virus that will cause him to morph into a Youma. However, he remained human with his personality intact. It turns out that he has the qualities of a rare breed of Youma which can transform freely from human to Youma and back, called "Kakusei-mono". However, he can't control it, and if he completely succumbs to negative emotions, he will lose himself.

Same with his other male schoolmates, he admires Rin. Because that same Rin plans to kill him if he completely loses himself to the Youma virus, he thinks of ways to seduce her and make her fall for him. He's a pure but perverted gentleman who lets his delusions run wild everyday.