Bloody Maiden: Juusanki No Shima

The following content is intended for mature audiences and may contain sexual themes, gore, violence and/or strong language. Discretion is advised.

Onitsuka Miaki, freshman from Fujimigahara Girls' Academy Naginata club, are going to remote island that owned by her captain, Igasaki Kotone, along with 11 members to do a training camp. Legends say that remote island is a place where the worst bandits lives and have national treasure beneath the island. Everything still normal before one of their member got killed. Their live-threatening experience begins now.
From Baka-Updates:
12 members of the Fujimigahara Girls' Academy's Naginata club arrive at a remote island belonging to the club president's family. Legend has it that the remote island had long ago been the hideout of a group of extremely cruel bandits, and that priceless treasures - the fruits of their plunders - are still hidden somewhere on the island.
All is well until their club adviser and two members are brutally murdered. Thereby the curtain rises on the surviving girls' life-threatening battle with a bizarre masked killer...