This anime is rather gory and upsetting depending on the viewer.
Several characters are hurt or killed, and some characters grieve over the loss of close friends.
One of the more violent scenes features a girl being eviscerated. Her internal organs are ripped out while she is still conscious, in order to remove a crystal fragment from her body. She is seen dying with tears in her eyes. A boy who was her friend attacks the killer in a fit of rage.
Characters often argue.
Some onscreen battle-type violence.