When Issei Hyoudou, an ordinary high school student with a penchant for lewd thoughts, is unexpectedly asked by his first girlfriend if he's willing to die, his world takes a bizarre turn as he is mercilessly killed. Just before his demise, the alluring Rias Gremory, a high-ranking Devil, intervenes by resurrecting him as a Devil under her command. Unveiling the longstanding conflict between Devils and Angels, Issei realizes his so-called girlfriend was a deceitful Fallen Angel named Raynare, on a mission to eliminate him due to his possession of a powerful divine weapon known as a 'Sacred Gear.' Welcomed into the Occult Research Club, the hub of the prestigious House of Gremory, Issei encounters Rias' other loyal servants. Embracing his new role as a 'Pawn,' Issei harbors ambitions of assembling his own charming harem. Yet, his path is fraught with peril, from skirmishes with Fallen Angels and rebellious Exorcists to the daunting task of mastering his Sacred Gear's formidable abilities.