MKON-148 · I'm a Loner Who Became the Target of My Sisters' Penalty Games and Had a Creampie Harem Sex Spree!!

My sister used to be cute, but lately, every time she opens her mouth, she says things like "You're gross, big brother" or "Don't do laundry with me." Then one day, she came home with her friends. She told me, "Don't step a single foot out of your room!" and I stayed quietly inside. Suddenly, I heard the thumping sound of someone coming up to the second floor. The next moment, the door burst open, and my sister flashed her panties at me. When I told her to "Die!", she immediately left. What on earth was that all about??
It seems I'm being used as the target for their penalty games, and the stakes are gradually getting higher. Eventually, I ended up having harem creampie sex with all of them!