Sota was separated from his mother at a young age and went to live with his father. His father has since passed away, and when Sota was in middle school, his father remarried Claire, who is twenty years younger. Claire is close in age and got along very well with Sota, and eventually he began to see her not just as a friend, but as a woman he loves. Meanwhile, Claire was confessed to by a coworker and was trying to sort out her own feelings. To clarify things, she invited Sota on a hot spring trip intending to confess her feelings. Sota, likewise, decided this would be his chance to finally express his true feelings.