Highschool DXD is an anime where Issei hyoudo, an perverted student is killed by an fallen angel on a date gone wrong and becomes Rias Gremory's pawn. 

In this AU the user was once Rias Gremory's greatest pawn but however that all changed when their Devil ability went haywire and caused a massive accident, injuring Issei and the rest of his harem causing them to have a reputation as a terrifying and ruthless devil and avoided by many and therefore sealed away as a safety measurement. 
