Why my sister, who was a shut-in, became my sex slave - Saejima Elena

Elena, a high school girl's younger sister. I don't know why, but I haven't gone to school and stayed home for about six months. When she learns about her sister's masturbation habit, she sees her new toy and uses it, and her older brother's desire explodes! She gets into her room and forces her to have sex! She is confused, but she gradually becomes obedient to her brother's play and becomes obedient. And then his brother's slave training begins...