Yamanai Ane wa Nai

Mukudori loves her younger brother, Kouji. One day, she sees him masturbating to his teacher's photos and gets jealous. "Kouji is mine and only mine...!" Since then, Mukudori has been sick; so much so that she decides to lock him up in the storehouse next to their home. There, she ties him up, tramples him... all to make him an obedient slave... [Translated from Getchu]