No nudity or sex.

The show has a lot of frequent action violence with punching, kicking, stabbing, slashing, crushing and shooting, but very rarely shows any blood. However, when it does show blood, it is a lot at once.

Frequent but often mild. The English Dub has less, so the Dub and Sub are rated differently.

Moderate language throughout the series.

Occasional smoking and drinking from adult characters.

The entire show is counted as a 'dark anime', meaning the storyline is intense, saddening, and often creepy. The appearance of the demons is guaranteed to frighten young kids. The concept of stolen and tortured souls exploited into weapons is very mature and dark. The storyline is in-depth, and is concerned with a lot of dark themes such as war, religion, loss/sorrow/grief, and the underworld and afterlife.

From around Episode 53 onwards, is when it starts to really get dark, intense, and violent. The earlier episodes are softened quite a bit by extensive use of comedy and sometimes innocent romance, but these are all but gone in the later episodes.