Stranded on an inescapable island......
Pleasures given by inhuman reduce the girls to estrus vessels......

Misaki Okita and her friends Rika Kimijima and Nagisa Amamiya
were just starting to enjoy a much-needed holiday...

Then:

Mid-voyage their boat capsized, dumping all passengers into the uncharted sea......
When Misaki regained consciousness she was sprawled on a coast.
Her head spun with vertigo......

She roused Rika and Nagisa who had washed up nearby, and searched the island perimeter.
After a while a woman's shriek came from the jungle thicket.
The girls arrived to the sight of a male corpse.......

...... and something unspeakable ravishing a woman.

She wasn't from the ship, but perhaps an islander or a tourist......
The girls barely had time to think when tentacle thing rushed at them.

* Despair cloaks a natural jail-like island where perils never cease...
* Penetration, pregnancy, birth, girls possessed by bizarre charm......
* Tentacles, bugs, aphrodisiac, bindings, bellies stretched, births delivered, humiliation at every turn...
How long can such disgraces be endured?

* Heroines forcibly incubate another species' spawn......
Their descent to the deepest seedbed of abnormal reproduction is a must-see event.

[From DLsite English]