Her husband is always busy with work and doesn't pay her any attention. Sara is trying to ease her growing loneliness by having immoral affairs with a man she met on social media who calls himself "Sensei". However, one day, she finds out that her husband's love for her, which she thought had cooled, is still directed towards her, and she breaks up with "Sensei". However, "Sensei" says that anal sex isn't cheating, and forcibly drags Sara into anal hell.