Amnesia Labyrinth Vol. 1

From the author of the acclaimed Haruhi Suzumiya series comes a new offbeat tale of murder and twisted love! When high school student Souji Kushiki returns home from summer vacation, he finds that his sisters Harumi, Youko and Saki have changed. Their strangely clingy behavior borders on the inappropriate and bizarre, yet Souji just brushes off their mysterious conduct at first. However, when Souji arrives at school the next day, he learns that, during the summer, three students were murdered by an unknown culprit. Are the victims linked, and could Souji's sisters have anything to do with the murders?