JUKF-067 My brother is my wank toy, Sato’s little Noka

Nonoka-chan, a girl who is more interested in naughty things than studying, stays at home all the time and peeks at her sister masturbating and having sex with her boyfriend. There is One day, a perverted older brother sneaked into Nonoka’s room and went night after night. Since then, I have been treated as a butter dog. Both are the same, but I wonder if it’s like this brother and this sister.