A bunch of girls with huge oppai who got tricked into making an eroge game… but wait, there’s a guy here? What could they possibly need him for?

His sister was always an over achiever, but now that she’s picked up an incest AND an anal fetish, that over achievement is starting to get to be a LITTLE bit much. The girl he had with him instead of being disgusted by seeing the brother and sister together…looks interested?!"