The death metal sequences can spook younger audiences, especially since most of them come out of nowhere.
Despite the screwball comedy, the show can have some really dark and depressing moments and tackles some mature topics like self worth and wondering what the point is in living when your life is putting you down. This stuff is usually saved for the last couple episodes.
Over all, not really meant for the little ones despite what the art style may tell you. There's almost constant swearing, some intense imagery and loud noises with the death metal scenes, and not to mention the mature themes and topics through-out.
(Deleted. Personal opinions about ratings are not appropriate for the Parents Guide.)
In one episode, Retsuko gets stabbed with a box opening knife.