病娇姐姐的「性爱」囚禁

"You'd better indulge in my love as heavy as a mountain
so deep as the ocean without having other people in this space..."

Your step elder sister Airi is the embodiment of ideal women as she very kindly takes care of everything about you like housework, private tutoring and so forth. But you come to think that it is overindulgence of spoiling kind so you set your mind to take some distance from her. Then Airi's too heavy and deep love drives herself into a crazy thoughts that finally she confines you!