Makoto lives a school life while living in a dormitory. The fulfilling three years are over in a blink of an eye, and the graduation ceremony is finally over. At his parents' house, Mariko, a woman he admired, remarried her father, and she rarely returned from her awkwardness. However, on the way home, Mariko, who became her mother-in-law, suddenly came to celebrate her graduation. That night, at her accommodation, she gently kissed "a gift for Makoto who has grown up." Guided by his longing mother-in-law, he climbed another staircase to an adult ...