Aoi, a beautiful girl who always puts a towel over her mouth and quietly looks around. In the spring of her first year at university, the college student (protagonist) who was in the same class as her in the classes she took, was curious about her. Attracted by Aoi's secret smile from time to time, when I took the plunge and confessed to him, he unexpectedly agreed to reply and we started dating. However, even after they started dating, Aoi's cool demeanor didn't change, and their relationship continued for days without progress. Wanting to get to know her more, the university student invites Aoi out on a date, but he learns of her surprising secret.