Ten years after divorcing her husband, Rina raised her son Taichi on her own, and eventually he landed a job at a real estate company. However, since it took over an hour to commute from home, Taichi showed no interest in moving out. Days passed with him never going out, taking breaks, or bringing home friends or girlfriends. Seeing this, Rina grew quietly anxious deep inside. Believing he should get out more, she decided to invite Taichi on a hot spring trip.