Mitsuko's daughter had married and moved out, but due to both spouses working full-time and struggling with household chores, Mitsuko ended up moving in with her daughter's family. Having lived alone for many years, Mitsuko had accumulated deep sexual frustration. One night, she went to the living room and accidentally discovered her son-in-law masturbating, even though he was supposed to be upstairs with her daughter. An awkward tension filled the air. When her daughter and son-in-law talked, he admitted it had been a long time since they last had sex. Mitsuko found her eyes drawn to his prominent bulge and impulsively asked him to help her relieve herself. Caught in the moment and overwhelmed by suppressed desires, their relationship took a forbidden turn.