11 Eyes

After losing his sister to suicide, Satsuki Kakeru drifts through a dull life. That changes when he and his friend Minase Yuka are transported, along with six classmates, to a bizarre realm known as Red Night. To survive and find their way home, the group must defeat six black knights. The story adapts the adult PC game 11eyes -Tsumi to Batsu to Aganai no Shoujo- by Lass.