Depression: (
Story/Location) Titles that contain characters who suffer from depression would fall into this category if this is of significant importance for the storyline.
Tragedy: (
Genre) Animes of this type have tragic events as an important part of the story, and usually will show how the characters are dealing with the consequences of that tragedy (more or less successfully). This doesn't necessarily mean the story cannot have a happy ending as the tragedy might occur during the first episodes of even before story begins; as such this category information need not be a spoiler (unless the tragedy were to be a surprise for the audience in a mystery-style show).
Violent: (
Objectionable Content)
Titles that include as an important part of their content excessive displays of cruelty, blood and gore. Any of the classical 'slasher' films would qualify for this keyword. The series
Black Lagoon would be a good example; as many of its chapters involve killer lolis, chainsaw mercenaries and flying body parts.
