Yuu dotes on her son so much that she finds herself in a relationship with a man and a woman. - The two, who now live apart, had been planning a hot spring trip for just the mother and son. - It was supposed to be an intense time filled with love for the mother and son, who met for the first time in a while. - but…. - When Yuu and his son arrived at the inn they were looking for, they immediately invited him to the open-air bath, where he tried to play with his body. - Two people washing each other's bodies and playing with each other in the open air. - The excitement gradually grew, and Yu was able to take his son inside. - As Yuu was walking down the hallway, having had a very satisfying time, he was suddenly stopped. - The person who stopped her was the so-called ex-boyfriend that Yuu dated before she met her current husband. - He grabbed Yuu's surprised hand, hugged him tightly, and started playing with Yuu's body. - He said in Yuu's ear that he was excited because of the mother-son behavior he had seen earlier, and continued to caress her, gradually exposing her lower body and making Yuu give him a blowjob. - Late at night, when Yuu was sleeping, her ex-boyfriend tried to make love to her. - Yuu's sensitive part accepts her ex-boyfriend in vain. - Yu can't help but moan and reach climax due to the violent piston, which is different from that of her son...