Yu entered a boarding school at the same time as her father remarried. His student life comes to an end in the blink of an eye, and on the day of his graduation ceremony... the one who runs to him with a smile is his longing mother-in-law, Kanna. Yu, unable to hide her happiness at the visit of her lover, celebrates with her that night. The two of them talked through the night, and their thoughts got through to each other. "A present for grown-up Yuu-kun," Kanna gently kissed. And he climbed another stairway to adulthood.