As Shinsuke, filled with secret admiration for his father's new wife Yurine, was about to embark on a dormitory school life, he thought that would help him forget her. However, student life flew by in the blink of an eye, and on graduation day, it was none other than Yurine herself who approached him with a smile. Overjoyed at their reunion, they celebrated together like old times. Yurine tenderly kissed him, saying, "Congratulations on becoming a fine man, Shinji-kun." And so, another step towards adulthood awaited him...

父の再婚相手・ゆりねに密かな憧れを募らせていた慎司。だがその想いを振り切るように寮制の学校へ進学するのだが…。学生生活はあっという間に終わり、卒業式当日。笑顔で彼に駆け寄ってきたのは、なんとゆりねであった。大好きな義母との再会に嬉しさを滲ませながら、卒業祝いをする2人。ゆりねは「立派な男の人になった慎司君へ卒業祝い―」と優しく口づけを…。そしてまた一つ、彼は大人への階段を上るのだった―。