In a world plagued by a deadly virus that eradicates adults, humanity falls under the control of power-hungry vampires who emerge to dominate, offering protection to survivors in exchange for their blood. Yuuichirou and Mikaela Hyakuya, orphaned youths, are captured by these vampires from their orphanage along with their chosen family. Dissatisfied with their subjugation as blood donors, Mikaela devises a daring escape plan that ends in tragedy, leaving Yuuichirou as the sole survivor. Rescued by the Moon Demon Company, a vampire-fighting military force, Yuuichirou joins the Japanese Imperial Demon Army with a thirst for vengeance against the creatures responsible for his loved ones' demise. As he navigates a world of betrayal and impossible challenges, Yuuichirou's quest for justice tests the limits of his friendships and loyalty in the face of overwhelming adversity. Enter the dark and thrilling realm of Owari no Seraph, a supernatural shounen anime that chronicles a young man's pursuit of retribution amidst the shadows of a shattered society.