After a tumultuous childhood following his parents' passing, Yuu Hasunuma lands under the care of his mother's cousin, his only reluctant guardian. Prohibited from entering the mysterious storehouse, Yuu's world shifts when circumstances force him inside, revealing a daunting yet captivating sight—a horned, hooved woman offering to grant his deepest desire at a grave cost. Yearning for familial bonds, Yuu strikes a deal with this demon, unaware of the perilous consequences that lie ahead.