I Witnessed My Sister Masturbating And My Reason Collapsed. I Don't Notice That My Sister Is Coming, And The Explosion Piston Is Done By Yoru Tsukigumo.

"I saw it..." -- My little sister's room is messy because she can't clean it. She's been wearing the same uncool T-shirt since middle school. She reads tons of erotic doujinshi and has bad eyesight. On top of that, she's a shut-in NEET. A classic loser girl... Of course, since we're siblings, I had no interest in her. -- But then I saw my little sister masturbating like crazy, completely seriously! At that moment, my morals, ethics, and reason crumbled with a crash. I turned into a sex monster lusting after my little sister! My sister's dried-up loser-girl pussy also awakened! I ended up repeatedly pounding her womb with creampies over and over...