Multiple people are shot onscreen, a man shoots his girlfriend by accident, a mafia member brutally slashes and murders multiple people with a supernatural weapon ability, a slaughter is heard offscreen, a teenage boy's leg is ripped off, but regenerates, a young girl is shot on-screen multiple times, but survives, multiple adults are shot onscreen, and much else. Lots of blood shown.
Minor acts of violence for comical effect. A man frequently asks girls to commit suicide with him and is in turn punched or slapped by another man. It's also implied the other man beats him up offscreen.
A boy collapses and is crying. A man then slaps him across the face. There are also flashbacks in which the boy is slapped by a man during his childhood.
A character throws a bunch of mobsters out of a window. The mobsters have funny faces while falling out so this scene is played for laughs.
The whole is pretty violent but not as much as something like Attack On Titan.
Two of the main characters are shown in a flashback episode to when they were 15-year-old boys, both members of the mafia. They have a battle with an enemy group of adults and kill them all except one man. The man is lying on the ground, dying of his injuries. One boy asks him if he wants to be killed as an act of mercy. The man agrees and the boy shoots him, but seems to have a bit of a psychotic break and continues to shoot him multiple times after he's already dead. While laughing with a deranged expression, the boy says it's more than the man deserves. The boy is also shown to be suicidal himself and longing for death, making the implications of this scene more mature and disturbing.
A character has a particularly violent ability to kill his enemies brutally but as this is animated the violence can be handled, but the scenes in which he kills are particularly gruesome.
It features lot of fantasy violence like aggressive behavior, hitting, fight/battling scenes by using with special powers, yelling, and automatic weapons. Some limited blood and injuries shown.