The members of the tennis club at Sakura Junior High School hold a class reunion on New Year's Eve. They are all twenty years old, and Mizuho is happy to see Tatsuya again, her secret love. At the reunion, they plan to stay at Mizuho's mother's lodge in a hot spring resort for a ski trip. Unfortunately, Mizuho's mother falls ill. She does not know whether she should care for her mother or finally give herself to Tatsuya.