If you're looking for manga similar to Ichi the Killer, you might like these titles. All recommendations are made by Anime-Planet users like you!
Meet Eiji Bando, a deranged, hentai manga-reading psychopath with a penchant for gunning people down. As a hitman, he works for the yakuza, causing plenty of collateral damage wherever he goes. Whether he’s joking about violating his male peers or just blowing people to bits, Eiji Bando always has plenty of disturbing fun in the process!
Though Gunmania is way less explicit than Ichi (if you've only read Gunmania you may be wondering how this is possible - TRUST ME), both are extremely similar. Both involve a complete psychopath carrying out senseless murders. If you liked one, try out the other.
Kazuhiko Amamiya is a detective who, after seeing the torture and subsequent death of his girlfriend, tracks down the man responsible for her death. Upon meeting the killer, Kazuhiko's psyche breaks and a new personality, the cold-blooded, arrogant psychopath Shinji appears and kills the murderer. More personalities materialize from Kazuhiko as he tries to investigate a string of murders years later. As he investigates, an intricate conspiracy plot begins to tangle up both Kazuhiko and Shinji as well as those around them.
Common themes in Ichi the Killer and MPD Psycho are: