There's a naked woman visible for about half of the end credits title; however there's generally something covering up her sensitive parts.

Multiple characters threaten the main character (who's a minor) in a way that has a sadistic feel to it, however nothing obscene happens.

In a comedic scene, a drunk girl throws off her dress and the bottom of her breasts are visible under the few clothes she's still wearing. Despite a boy's protests, she releases the last button right in front of him though the viewer doesn't she anything at this point.

In one scene, a girl wears nothing but a blanket. Only her legs and bare back are shown.

A few female characters wear short skirts. One minor character shows some cleavage.

A man transfers an antidote drug to a dying girl via mouth-to-mouth. Later, a girl does the same with another girl, only with poison.

A girl smiles and gouges a man's eye out with her finger. You see a spray of blood and he screams. Then you see the girl holding his bloody eyeball.

A girl falls dead on the ground, covered in blood, next to a pair of bloodied scissors.

A cat is shown bloodied on the ground after a boy gouged its eyes out with a pair of scissors.

Combat with swords, guns, fists, and other weapons, as well a monsters known as 'chains' that possess various abilities.

Uses of crap, damn, dammit and hell in the official subtitles infrequently.

A boy calls another boy a midget, this is moreso humorous than ableist since both boys are teenage.

A character smokes

In one episode, the characters all get drunk. Though some may look it, none of them are minors.

Various monsters called 'chains' inspired by Alice in Wonderland. These range from small creatures like living dolls to enormous monsters. The vast majority are very frightening if not subtly disturbing.

Occasional flashbacks to a city being destroyed. You see bloody bodies lying everywhere and buildings burning.

When an illegal contractor's time is up, them and their chain are swallowed by the Abyss. This is always very intense.

One particular chain can turn people into puppets and use them against each other.