Yuiko Kubozuka, a 17-year-old high school student, has a unique bond with animals, yet her intense affection always drives them away. One stormy night, she accidentally startles her own cat, leading to a mysterious boy rescuing the feline with a silent demeanor. To her surprise, the boy turns out to be the enigmatic transfer student, Leo Aoi, feared for his wild appearance. Despite initial apprehensions, Yuiko musters the courage to thank him, discovering Leo's gentle nature and affinity with animals that sparks her envy. Beneath his intimidating facade, Leo harbors a dangerous secret: the sight of blood triggers a primal transformation, endangering those around him. Can Yuiko help Leo control his inner beast, or will his untamed instincts drive him away like the rest?