Saki's son, Yuuki, was invited by his classmate Masaru's mother, Yurika, to go on a hot spring trip with two sets of parents and children during one spring break. In fact, Yuuki had been admiring Yurika's beauty and charm for some time. Thanks to the mixed-gender hot spring at the inn, he finally got to see Yurika's naked body as he had long hoped. Unable to calm his excitement, Yuuki sneaked into Yurika's bed and had sex with her. Then, their adulterous relationship was discovered by Saki, who also became aroused because she loves Yuuki so much…
