Right after his father remarried, Yu left home to attend college. After a fulfilling campus life, graduation day arrived. On his way home, his stepmother, Ikumi, ran to greet him with a smile. Harboring a secret admiration for her, Yu, who was traveling alone, reignited his feelings upon this unexpected reunion. That night, they spent a graduation celebration together, and Yu sent Ikumi to her hotel room. Even in the room, their conversation flowed endlessly, until Ikumi, saying "A present for the adult Yu," sealed their lips together.