My NEET, busty older sister started a strange business at home. (Yoshida Ayane HBAD-699)

My older sister, Ayane, neither works nor goes out, living a life of freeloading off her parents. But recently she's suddenly become quite wealthy, and I'm worried she might be stealing money from us. It turns out she's actually been soliciting customers online and running a erotic spa for men in her room. I can't stand hearing those erotic sounds every day, so I've been saving up my allowance to beg my sister for money...