Nonoka, a girl who is more interested in naughty things than studying, has an older brother who stays at home all the time and spies on her sister masturbating or bringing her boyfriend along to have sex. - There is. - One day, the perverted older brother sneaked into Nonoka's room and went there night after night, but he made a mistake, and from that day on, the power relationship reversed and the idiot older brother turned into a servant. - Since then, he has been treated as a butter dog. - They're both the same, but I guess you could say there's an older brother and a younger sister.