Shimogami NTR who should have been tampered with, but the situation is reversed and he becomes crazy enough to make his sister go crazy. Yuzuru becomes like a sex toy when she peeks at her best friend's older sister's masturbation, but with a powerful Mach piston that does not match the looks that seems to be quiet, her best friend's I will captivate my sister! !! The relationship between the two gradually escalated, and the secret secret of the sister and best friend drowning in pleasure! !!