In this steamy tale, lovers "Machi" and "Ken" are both very passionate individuals. Machi has a dominant side while Ken leans more towards being submissive (S) and enjoys being dominated (M). Unbeknownst to them, their father Hiroshi overhears strange sounds coming from their room one day and decides to investigate further. What he sees shocks him - his son being pleasured by Machi through anal intercourse! From that moment on, Hiroshi becomes obsessed with Machi. She seems to sense this and teasingly entices her boyfriend's father, eventually leading him down a path of forbidden pleasure when they find themselves alone together... Note that the specific contents may vary depending on the distribution method used.