There were a few disturbing scenes in this movie. One early in the beginning, and most in the later parts. I'm the type of movie viewer that goes out of my way to avoid violence and gore, and I didn't see this one coming from the description and being that it is billed as a comedy.
But having said all that, I found it to be an interesting look into Japanese life that we never see including scenes of run down neighborhoods and poverty. Also the way the gang communicated to each other goes against everything we were taught or shown about Japanese culture.
I think it's a good movie. The gore and the one disturbing scene was totally unnecessary in my eyes. If that had been omitted, I would probably have given this a rating of 8 or 9.