Part 2 of the second part. If you want to watch the Third Gangster films, it really pays to do a little investigating up front, since these films have tightly interconnected plots and watching them in order is probably the best way to go. Not that you'd be completely lost if you start with this part, but you will be missing out on some useful backstory.
After the death of Soma, Masaki vows to find the killers and starts his own investigation. In no time he finds himself tailing Karasaki, but the more he learns about the murder, the clearer it becomes that Karasaki is only a pawn in a power struggle between Masaki's bosses. When they learn Masaki is digging into Soma's death, he becomes a target himself.
The film reminded me somewhat of Rainy Dog. It has all the usual crime/Yakuza element you'd expect to see in a Miike, but it also has these quieter moments. And there's even room for some sneaky comedy (the Léon references stand out). Not Miike's best, but if you're looking for solid crime filler, this one won't disappoint.