"Demons are attacking earth, releasing a field that drives men to lust after anything female. Angels Yuuri and Suzune decide to fight these creatures of darkness and save the world. Though, maybe the men don't want to be saved..."
Demons possess a bunch of dudes who in turn gang fuck the shit out of a bunch of magical girls and turn them into sex slaves who love it. Basically the teachers and principle at their school end up fucking them. It's pretty great, it's BDSMy and turns into happy magic fuck by the end of it. (IE It isn't because they love it.)