Last Waltz: Hakudaku Mamire no Natsu Gasshuku

Fuente: AniList

It was just supposed to be a summer training.... Yuki is a caretaker of the baseball club. She and other members stay at a training camp on the isolated island now. But one day, a civil war breaks out. Male teachers leave the island to see what's going on. However, they never come back. Several days later, they know that their ship is wrecked. Nothing to drink.... Nothing to eat.... They gradually lose their self-control.... (Source: ErogeShop)