Oni Harami no Gakuen ~Sukumizu Shoujo Ishukan Ryoujoku Geki~

An academy located deep within the mountains and surrounded by nature.
There are approximately 500 students at this originally all boys academy.
This year it became co-ed and our heroines Rin and Mayu newly
transfer to the school... only for something absolutely abnormal to occur!

The students are turning into monsters and the school has
transformed into a tentacle writhing cesspool of downright decadence...

Behold and revel in the hard core tentacle play and situations!

[From DLsite English]