HUNTA-283 "To draw a realistic erect dick!" My sister is an erotic manga artist. However, she seems to know nothing about men's bodies and always leaves them to her assistant. But even that assistant is a virgin, so I get called to my sister's apartment s

The sister who draws erotic manga doesn't know about male bodies, so she leaves that part to her assistants. However, those assistants are all virgins! So, my sister summoned me, her brother, to her apartment where she works, using my body as reference material! 'I need a real erection to draw!' she said, forcing me to get hard, then 'I want to see the face of someone getting a blowjob!' 'I want to see the face of someone about to cum!' and they messed with my dick all over the place. Finally, they even said, 'I want to see what it looks like when you're fucking!' and I ended up having sex with all of them!!!