성별 : 남성 생일 : 키/몸무게 :
사립 쿠오우 학원 2학년. 망상벽이 심하고 야한 것에만 관심이 쏠려 있는 공인 변태로 교내에서도 여학생들의 따가운 시선을 받기 일쑤이다. 생전 처음 사귀어 본 여자친구에게 갑자기 죽임을 당하지만 리아스에 의해 악마로 부활, 리아스의 부하가 되어 오컬트 연구부 소속이 된다. 계급은 병사(Pawn)
Rias begins to develop feelings for Issei in Volume 2. He remains ignorant to her advances though, viewing them as the adoration a master would show a pet. He continues to misunderstand Asia's feelings as well until Volume 6 when she kisses him. Akeno admits she has feelings for him in Volume 3 and begins actively pursuing him with flirtation and seduction. Koneko warms up to him after Volume 5 and begins to develop feelings for him as well. In Volume 10, he confesses to Rias that he loves her and she returns his love. They start dating afterwards.