Mariko is delighted that her married daughter remains at home in a two-family household, and she gets along well with her son-in-law Takuto. Lately, however, he has been working remotely more often, and she repeatedly catches him masturbating. He explains that his cock is so large that he and her daughter have stopped having sex. Sex-starved by her own husband, Mariko tells herself she is helping the couple and begins servicing his huge cock to ejaculation. As she handles his shaft day after day, the desire she has kept buried deep inside starts surging to the surface...