I just finished this series and thought I'd use this final volume here to discuss it as a whole.
Although I was a big fan of Takashi Miike's Ichi the Killer back in the day, I hadn't checked out this source manga recently and, considering the film's reputation as a landmark in cinematic extremity, it's a little surprising to see that it is, for the most part, a very faithful adaptation. Indeed, basically all of the movie's most notorious moments are taken straight from the books. Even more surprising though, is that it actually toned things down a notch as well. There are a handful of subplots in here, such as one character's necrophile tendencies, that are quite shocking, not in the least as I wasn't expecting them due to their absence in the film. There are also a few sequences of extreme, blackly comic violence that are honestly quite funny here, even if I can see how they would be much harder to pull off on-screen. While the whole manga throughout is very well-paced and gripping, around half-way through I started dropping my star ratings from 4 to 3, for one main reason. Don't get me wrong, I came here for a violent, transgressive experience, but by the time a couple of truly vile villains are introduced, the manga's treatment of its female characters just shifts from enjoyably depraved to just downright ugly and unpleasant. Given how darkly comic and over-the-top most of the violence is, the amount of rape and torture inflicted on literally every female character just serves to make the whole thing start to become a bit too off-putting at times.