I returned to my parents' house after a long absence. My sister Yayoi and I were very close when we were kids, but ever since my rebellious days, our relationship hasn't been good. When I saw her again after many years, she had grown up to be sexy and attractive. But she is not fully mature, her panties are always exposed ...... or is it really exposed ......? The fabric is so deep into her buttocks that it doesn't cover her full buttocks at all. How could I possibly arouse the sexual desire of someone like my sister?...... Later on, my parents went out on a trip. Even if there are only two of us at our parents' house, her panties are always glistening. I couldn't contain my sexual desire for my sister. Once I make a move, it's over, and then when my parents aren't around, we'll just keep having sex. My sister can't be this cute ...... or this sexy ...... but even if I thought so, I still insisted on having sex.