There is a perverted brother who has failed his exams and is always peeking at his sister Mai-chan, who is more interested in erotic things than studying as she gets older, staying at home all the time and watching her masturbate or bring her boyfriend in for some fun. One day, the brother sneaks into Mai-chan's room and fails in his usual nightly activities, and from that day on, the power dynamic reverses, and the brother becomes his sister's servant, being treated like a butter dog from his sister on a daily basis... This brother and this sister!
