Death's Reflection

Stolen from back Amazon:
In this second volume of four novelas, Hino continues his theme of the intertwining of innocence and evil in shojo horror manga style. When Yuki and friends discover a corpse reflected in the bathroom mirror at school, they believe it to be a joke. However, gruesome events unfold that will lead them to regret they were ever so foolish. Other stories include a girl whose beauty makes her the victim of a terror campaign; another who is bullied by a teacher but, in death, achieves her revenge; and classroom 3.7, into which students enter but never leave.