Rank: Low-class Devil → Middle-class Devil Role: Pawn (8 Piece
, later in volume 12 it is revealed that 4 of them are Mutation Pieces) Species: Reincarnated Devil (Former human
until Volume 11, becomes Humanoid-Dragon in Volume 12) Sacred Gear: Boosted Gear (Longinus) Weapon: Ascalon Power: Dress-Break, Bilingual. A second-year high school student attending Kuou Academy. He is known to be stupid, lecherous and a pervert among his peers. A normal high school student born in a normal family, but is in possession of the Sacred Gear "Boosted Gear" which is listed as one of the ultimate Sacred Gears (Longinus). He was killed by his first girlfriend, a Fallen Angel, and was revived as a Devil and a servant of Rias Gremory, his new master. Now he aims to become a Harem King by gaining a peerage, unaware of himself attracting girls around him.
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.