Reiko dotes on her son. And before she knew it, they had become in a forbidden relationship, overlapping and loving each other. Reiko and her son planned to enjoy a long rendezvous with her son in a private hot spring, so she came to a hot spring inn with her son. After checking in, her son immediately reaches out and wants to have sex with Reiko. However, she dissuades him with her motherly face and invites him to a private bath. The open atmosphere lifts the mood of mother and son, and when her son kisses Reiko, the mother and son can't help but devour each other's pleasure. There was a man secretly filming them. This man, who happened to be at the inn, is Reiko's ex-boyfriend. He had passed Reiko and her son at the entrance earlier, but Reiko didn't notice. After a long bath, the man called out to Reiko as she walked down the hallway. Reiko was suspicious when he called her name, but when she realized that the man was her ex-boyfriend, she was shown a picture on his cell phone. The man grabs Reiko's hand, who is upset that her relationship with her son has been discovered, and takes her to a secluded place. Her body is hot and sensitive from her previous act with her son, and the man's caresses bring her to an unwanted climax. She manages to make the man ejaculate with a blowjob, but the man takes Reiko to his room and rapes her. After being made to cum many times by the men, Reiko staggers back to her room. After dinner, Reiko opens her body to her son at his request, but she feels unsatisfied with the act with her son. Late at night, Reiko wakes up alone and heads to the men's room...