If you're expecting a Yakuza game in the Sengoku period... well, perhaps you found it. Maybe.
In this game, you're in the role of Kazumanosuke Kiryu, a samurai who was previously known as Miyamoto Musashi (also known as the founder of the nittouryu - two sworded-style), who fought in under Mitsunari Ishida's banner and fled from the Battle of Sekigahara after killing one of Ieyasu Tokugawa's relatives. He leads a normal life doing favors to other people (pretty much an excuse so that he wouldn't lose the Yakuza essence) until he meets a little girl (Haruka), who asks him to do a single favor: kill Miyamoto Musashi, who exterminated her family.
Unfortunately, for us Westerners, this game did not get an English version, so I had to try to survive the way I could with my limited Japanese skills. I could get the gist of most of the missions since, like in the games of the regular series, there is usually an indication in the map saying where you should go. If you're one of those people who enjoy doing a 100% completion in the game, this may be a little bit more difficult if you don't use a guide, though, because some of the subquests require some Japanese understanding. I only know a little bit of the language, so I couldn't do more than understand the main points of the story and, sometimes, knowing what to answer in a couple of subquests. What made it worse were the kansaiben (Osaka's dialect) present in most part of this game.
As for the game itself, I must say that I didn't get that much frustrated since I decided to play the first games of the series, for the Playstation 2 console. Yakuza 3 had a nearly flawless gameplay, but in this one I just couldn't understand the purpose of using a sword, since fighting barehanded seemed more effective. You can choose to use a regular katana, a short sword, a heavy sword, fight bare-handed and use two swords, but the moveset for each of the weapons is so limited that I didn't feel motivated to choose a specific one. As you level up your character or make some subquests, the amount of moves variety increases slightly, but I still spent most part of the game thinking of how great it would be if each weapon had a greater variety of attacks... or at least more Heat Actions. The style I used the most was the Nittouryu, but after a certain part of the game, I got tired of seeing always the same Heat Actions. Not only this, as you play this game you'll notice that you don't really cause too much damage using regular attacks with your swords and soon enough you'll feel that fighting bare-handed actually causes more damage to the enemies (since you can use throws when you're not equipping any weapons) than equipped.
Another thing that got a LOT in my way during the fights was the camera position. It was awfully frequent to lose Kazuma in the middle of the furious enemies around him because the camera refuses to be set in the right place, which also turned up the controls even more inefficient.
And speaking of flawed controls, the target lock that was once marvelous in Yakuza 3 is crappy again in Ryu ga Gotoku Kenzan. There is one aspect of the game that may be the reason why the target lock fails so much: the amount of enemies you have to face all at once. Perhaps the target lock even works as in Yakuza 3, but you rarely face a single enemy at once, so the target lock will remain locked in a single enemy, even if he is downed. This may not seem such a big problem, but when all of your battles (except for a couple of boss battles) are against multiple targets, this get really annoying.
I read Eiji Yoshikawa's Musashi book, so I understand that most of his battles put him in disadvantage, but this game takes this to extremes. You will face annoying enemies that always walk in large groups and some of them are terribly annoying (more specifically the ninjas, the sword-sheathed-style samurais and the sumotoris), which makes the battles painfully time-consuming and boring.
Good things about the game? Well, you have several minigames of the regular series are present in this game, including the gambling games and the hostess events (but, again, you'd have to understand Japanese to feel comfortable with the hostess events). There are even the Revelations from Yakuza 3, but adapted to the Japanese Sengoku era. Fantastic. Plus, a couple of new minigames to level up your character, like the Watermelon Cutting and the Meditation. There are also bounties and the coliseum. But that's all. As for the storyline, who knows a bit about the Japanese Sengoku era will feel quite familiar with the characters and places. You are free to run through seven different cities AND this game, like all the other Ryu ga Gotoku games, offers the player a Premium Adventure after you finish the regular Story Mode.
Now, if this game were to be released in English, I'd think twice before saying that "I'll definitely replay this game". The times it got me frustrated don't make me feel quite happy with it. I'd rather remain with the regular Yakuza series.