MIAA-057 Sister-in-law discovered that her younger brother liked to masturbate

My younger brother (me) is beautiful but gets aroused all the time despite being bullied by his stubborn older sister. It seems like she will get married soon, but I know that my sister was once a yankee bitch and pervert in the past. I will use this as a joke to force my sister to do it! Until now, I've been spying on sex with men, and it's time to give the results of my research on how to make my sister feel and cum.