Rena Momozono has harbored a pure, unwavering crush on her neighbor senior for a long time. Even now, her feelings haven't changed, and she joins the same company where he works. However, her senior ends up getting a girlfriend... Rena, burdened with unrequited feelings, is unexpectedly asked by her senior to practice sex with her, saying, "How about I be your practice partner?" Despite not knowing his reasons, Rena experiences the fleeting joy of intimate moments with the one she loves. This is a steamy love story where secret practice sessions bring the two closer together.