[Gerupin (Minazuki Juuzou)] Yukari to Takeshi no Fucking Sankan-bi [Pirate]

Busty housewife Yukari and young Takeshi think their secret sex-friendship is safe until his mother Maki—a poised esthetic salon owner with a taste for teasing—catches them and lays down her own ground rules instead of ending things. What begins as an embarrassing spread-eagle inspection of Yukari's freshly shaved body melts into lingering touches and heated chemistry between the two women, all while the threat of Yukari's husband finding out looms overhead. When Maki invites herself to watch Takeshi's high-speed strokes drive Yukari into a sweating, tongue-lolling frenzy, the so-called observation day becomes a greedy three-person arrangement nobody wants to give up.