Tsukasa lives a life of luxury without a care in the world. Her husband, Shinichi, is a renowned patissier, but treats her like mere "ingredient," coldly engaging in frequent sexual relations. Meanwhile, Mamoru, Shinichi's stepson, deeply adores his stepmother Tsukasa. One day, after discovering Shinichi's dark secret, Mamoru anonymously sends a letter to his mother. This letter triggers a dramatic shift in their relationship. The seemingly pure and gentle young mother, Tsukasa, reveals her hidden side as an intensely lustful aggressive woman. As Mamoru gives in to her desires, their relationship escalates into something shockingly lewd and taboo.