A high school student reincarnated as a devil, Hyoudou Issei, nicknamed "Issei," strives to fulfill his dream of becoming a "Harem King." He battles various opponents, including gods, devils, and fallen angels, overcoming crises with热血 (passion),色情 (eroticism), and unimaginable opportunities to save the female leads. Starting as a low-level devil, he continuously grows stronger! Currently, he's participating in the Azazel Cup, an international ranking game involving various factions. He continues to work hard, both in battles and as a devil.