Kurokami Kyonyuu Iinchou to Souta-kun no Natsuyasumi

Yuri's molesters have finally been sentenced to prison leaving her and her sister Shiori with peace and a normal life.

Souta is Yuri's cousin. His parents are going on a trip, now Yuri and Shiori are taking care of him. At first he was obedient, but he started being mischievous. He treats Yuri as his toy, like grabbing her breasts in the bath, or storming in the toilet while she is inside, and sleeping together and fucking her at will. Involving  Shiori, he forces them to walk around naked in the residential area, and makes them go into the convenience store. They are truly doing whatever he says...!?