As for the tags though, I do sorta wonder why "het" would be there? As far as what happened, the opposite pairs didn't really interact at all. I'd see it more as a straight up yaoi/yuri work.
The problem of how on earth to even describe what goes on here is the reason for that. I mean, in the opening where he's jerking off in the middle of class, is that just masturbation? Or het, seeing as his dick is a girl?
This manga raises many important questions.