Name of hentai anime? :O

Hello. :)
I'm new here, and I very much hope you guys can help me, thank you. :D

Here it is: I've watched a hentai anime before and liked it very much, but just can't seem to remember its title/name. I remember the plot thou. :O
The plot was about 3 girls, part of a student council, protecting the school from youkai (demons) with their powers. They fought valiantly but lost to the youkai because their teacher was helping the youkai (the teacher had powers too and was a slave to the youkai's dick). In the end, the stuco president was forced to give up her virginity to the youkai in human form in front of the entire school while addressing the school one day as the youkai threatened to kill everyone if she didn't comply. She tried to resist but eventually got broken by the youkai.

There were some tentacle scenes, and the last part of the rape included the principle and vice-principle of the school too. With triple penetration. The stuco president was a long haired brunette with red eyes, and one of the stuco was blonde. I forgot about the last one. This anime included creampie scenes as well.

Would appreciate it very much if someone could help me identify this anime, thanks!