Two years ago, widow Yuu lost her husband in a traffic accident. She lives with her stepson, Shinkuro. After his father's death, Shinkuro dropped out of college, never found a job, and has since become almost a recluse. Worried about him, Yuu continues to support him through daily life. But her concern goes beyond mere parental care—Yuu is increasingly aware of Shinkuro as a man. The reason she hasn't left the house since her husband's death is because she's in love with Shinkuro. One winter day, under the pretense of "changing the scenery," Yuu decides to invite Shinkuro on a hot spring trip.