Rin-san (33 years old). A married woman of ten years with two children, she shares a table with a male classmate at an izakaya just before the last train. Excited by drinking after a long time and by physical closeness with a man other than her husband, her heart races. Bound by their shared past as high school classmates, they deepen their conversation while hiding their true feelings. When their friend steps out to the restroom at a karaoke box, the two exchange a kiss. In the love hotel bath, she experiences bathing together with her classmate for the first time since their school trip. Their relationship is about to enter a special, one-night-only connection. Riding him in the cowgirl position, Rin grinds her hips on her own, expressing her passionate emotions. A night overflowing with the allure of adult desire, long forgotten.