Mariko is happy that her daughter has stayed home after getting married, so now they are living together as a two-generation household. She gets along well with her son-in-law, Takuto, but he's been working remotely more and more recently. She even catches him masturbating frequently... When she asks him what's going on, she learns that his dick is too big, which is why they haven't had sex in a while. Mariko, who has been feeling frustrated by not having sex with her husband for a while, makes the excuse that she's doing it for her daughter and son-in-law, and makes him cum with her...