Des：One spring break, Sakis son, Yuuki, is invited by his classmate Masarus mother, Yurika, and they decide to go on a hot spring trip together. In fact, Yuuki has long admired Yurikas beauty and sex appeal. At the inn, thanks to the mixed bathing hot spring, we witness Yurikas long-awaited nude body. Still excited, Yuuki sneaks into Yurikas bed and has sex with her at night. Yuukis mother, Saki, also finds out about their illicit relationship, and Saki, who loves Yuuki, gets excited...