After a divorce, a middle-aged man lives a lonely life—until his niece Mahiro suddenly shows up, having run away from home following a fight with her parents. She moves into his house uninvited and begins living with him. Having always felt close to her uncle, by the second night Mahiro initiates a sexual advance. Though initially hesitant, he gives in to his uncontrollable desires, and their affectionate cohabitation begins. As feelings grow between them, a new relationship blossoms.