One summer vacation, Yuya was invited by his mother Manami's friend Yuri to go on a three-day, two-night trip to Tokyo with the two mothers. In fact, Yuya had long admired Yuri's beauty and glamorous body. At the inn, he thoroughly enjoyed watching the two mothers change clothes, and in the mixed-gender hot spring, they washed each other's mothers' bodies. Yuya, excited to the peak, sneaks into Yuri's futon and has a nighttime affair, but soon Manami, jealous of Yuri, joins in...