I returned to my hometown after many years of studying and working in Tokyo. My older sister is still the same, still a hikikomori, spending all day in her room playing games. She wears a loose shirt, doesn't wear underwear, which makes her breasts appear in front of me. When my mother went shopping, I accidentally discovered my sister masturbating in her room! Unable to resist her seductive look, I went in and inserted my penis into her vagina! It seems like she didn't intend to avoid it, even cooperating with me! And after that time, she actively came to find me, and we secretly had sex during the time I stayed here...