In a world where half of the people evolved differently from animals, a tough and fierce wolf named Shirou is often misunderstood due to his striking appearance. Shirou is in love with Usami, a duck with stunning brown skin. Although Shirou, being a carnivore, makes Usami feel insecure, after the wolf saves her from an assailant, Usami shows a vulnerable side that no one else can see. But then, Shirou begins to desire to mate with Usami!