Tomoko is an I-cup high school girl who loves her big brother! She feels a motherly affection for her sloppy brother who is a college entrance exam retake student, and is a devoted and kind girl who cheers him up with the naughty service she just learned and her huge I-cup breasts. Her parents will be away for the night, so Tomoko is full of energy from the morning! "Big brother, let's play lots of naughty things with Tomoko today!"