What if... a male and female friend who missed the last train went on a sex adventure in a mixed bathing hot spring...?! When the male and female friends touch each other naked, will their sexual desires increase even though they had never thought of each other as the opposite sex before? Mizuki is a hairdresser. Daiki is a hairdresser. Hina is a second-year university student. Touki is a fourth-year university student.