Hanshoku Gakuen ~Shoujo-tachi o Esa ni Hanshoku ga Hajimaru~

School is a writhing sex hell... and the female students are the lures---

Blue Ivy Academy was devoured in a horrifying tentacle assault.
A massive organic wall of slimy tendrils came to life and ravished every snatch...
The girls panicked. Everywhere you could hear young ladies slopping wet.
Every last male student was slaughtered, and every last girl will be enslaved.

A few heroines have miraculously survived.

The only sounds here now are slurps and moans of mindless fornication.
As the tentacles evolve, there's nowhere to hide.

These girls have seen the end of the world...

It's impossible to simply run. But the girls are planning a daring escape...

[From DLsite English]