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