Kangokutou

It was supposed to be just a peaceful field trip. A high school was taking a ferry to school trip, only for it to end tragically as the ship ends up getting hijacked, and only a handful of students were able to escape and survive to an island with no name.

So began the survival of the fittest, as the island was filled with more men than women -- 100 men and only 4 women, including one teacher -- the women did their best to fight against the overwhelming waves of men, proving that they can be better even with lesser forces.

Before long, there was no hope of rescue, so many of the male students started losing their minds and reasoning, starting to act instead on their desire and libido. At the same time, our four heroines have to fight against the hordes of men to whom they are only objects of sexual desire.