Hmm, they're not the most fleshed-out scenes, but at the College in Act 2 the naughty scenes you can eventually get with the basketball girls and while teaching a class are technically orgies? Or at least right on the cusp of being an orgy.
If nothing else, they are foursomes.
EDIT! OH! OHHHHH!!! That super awesome scene with the volleyball team! That is definitely an orgy! MC + 8 girls, all properly given "training." You sly dog, trying to make me forget about that one by claiming there are no orgies! :P