Staying at his uncle's house in Tokyo while preparing for college entrance exams, the protagonist finds himself living with his uncle's wife, Mako. A graduate of a prestigious women's university, Mako was supposed to help him study. However, one day he catches her in an intimate moment with his uncle. Seeing her sophisticated sensuality, dressed in luxurious lingerie, completely shatters the rural, virgin boy's composure—study becomes impossible. Soon after, Mako moves close to him, whispering, "You saw me yesterday, didn't you?" as she gently presses her lips to his, marking the beginning of a new relationship.