One day, while cleaning her son Taichi's room, Haruna notices a pornographic magazine on his bed and ends up reading it. Haruna is naturally perverted, and has recently been sexually frustrated, so she gets excited and starts masturbating on the spot. Just then, Taichi comes back from outside and comes into the room, seeing her in a disheveled state. When questioned, Haruna brazenly accepts and starts sucking Taichi's dick, but then her brother Makoto sees them in the act...