Finished the five film series
Battles Without Honor and Humanity. AWESOME! That is the only word to describe this Yakuza Odyssey. All five films follow a single story arc following a core set of characters over ~24 years. From their post-war days on the street, to becoming becoming Yakuza and eventually all moving up the ranks or being killed. Think of combining Goodfellas (scope) and the Godfather into a single Gangster Epic. Oh and its supposedly based on true events, which makes it even more interesting.
Warning: This can be
VERY difficult to follow as there are dozens of characters who are introduced very quickly. Many die and new ones are introduced. Combine this with that many characters appearance alter as time and status change. So expect to not realize one guy on screen was a member of the other guys family two movies back.... but its ok, just roll with the punches and you will have a great time. The most significant characters often have defining features or habits that make them recognizable throughout.
While this series does have a lot of violence, most (but not all) is gore free and often kind of humorous due to the frantic nature of the men delivering the damage. The Yakuza accuracy with firearms seems to be just below Imperial Storm Trooper.
As expected the films focus heavily on the political/organizational structure of the Yakuza families and the back stabbing and back door deal making that occurs in the pursuit of wealth and power. One break this series makes from other Yakuza stories (from my limited perspective) is that they make most Bosses out to be very weak men who rely entirely on their (young) soldiers to keep them in power. One boss in particular becomes known for crying when he cant get his way so his men will feel bad and do whatever stupid thing he wishes.
Will most definitely be watching this series again multiple times in the future. An absolutely mesmerizing tale that's ending was bitter sweet.
TL;DR If you are interested in Yakuza films, this is where you should start.