Keiichi Nanase lives under one roof with his five younger sisters.
Younger sisters who are growing up around the age. Keiichi often felt unhealthy when he saw them.
And then the summer vacation. Keiichi’s parents go on an overseas trip.
Her serious sister, Rina, thought that her sloppy and naughty brother would become more and more vulgar while her parents were absent, and she took a strict attitude toward Keiichi.
However, while she says she doesn’t like naughty things, she secretly masturbates Rina.
And Keiichi happened to know that …
