have you heard of vmware fusion?, you should be able to play *most* hentai games made for PC on a mac, even a few older 3d ones.., vmware fusion is only for macs and has directx 9.1C + shader model 2 support. so can support many even modern games..
on a linux machine i used VMware player and figured out how to make my own blank hard disk from files i downloaded, loaded my windows xp cd booted the virtual machine, installed windows XP sp2, japanese localization, did a few tricks to get directx9b to work and i could play in full screen like i was still on a XP machine. I could even let it only use 1 of my cpu cores.