Kambei may call the shots, but Kikuchiyo is the guy we can't take our eyes off of. He's the outsider in this gang of outsiders, the one who doesn't fit in no matter where he goes. He's plenty cranky about it too, but he's determined to make it work no matter how many times that darn horse knocks him off.
Like the other six samurai, we don't know a whole lot about him before he drunkenly stumbles into the frame. We do know, however, that he comes from peasant stock. "You were the son of a farmer?" Kambei knowingly asks him. He has no noble blood or training, and in strict terms of Japanese culture, he has no business being a samurai. He should be out farming the fields, not carrying around a ridiculously huge sword and itching for a fight. (Are we compensating for something Kiku?)
More than a Farmer
And yet he pushes on, determined to rise above his station and be measured for something other than growing rice. Had he lived in another era, it wouldn't have been possible. But during this period of Japanese history, law and order has broken down and the unthinkable act of caste-hopping suddenly became a lot easier.
Kikuchiyo becomes the life of the party, swaggering into these po-faced killjoys and showing them how to drink deep from life. In many ways, he's the comic relief. He can't ride a horse to save his life, for one thing, and when it comes to getting drunk and making a blabbering imbecile of yourself, this guy has cornered the market.
But underneath that, there's something really subversive about this character, and not just because he's interested in wholesale slaughter. He's the son of a peasant…and when you're the son of a peasant in Japan at that time, you didn't get to be anything but a peasant.
Kikuchiyo wants more than that. He knows what society thinks of him, he knows that he really should be out in the fields planting rice, but by gum, that's not what his heart tells him. And he's gonna follow his heart all the way to the end of the line.
We're used to these characters in America, but in Japan they're something entirely different. Square pegs like him tend to get pounded into round holes, and putting your own wishes ahead of the greater good is a serious way to end up sitting in the corner thinking about what you've done. His behavior, and the fact that the film seems to endorse it, represents a big change from the way things were supposed to be… kind of like Japan itself, which was learning how to deal with the distinctly Western idea of individuality when the movie came out.
More than anything else, Kikuchiyo is a walking symbol of this changing perspective: scruffy, belching, marching to his own beat and not a bit sorry about it. We see that in the creation of the banner where the other samurai get circles but "you're so special, that I made you a triangle."
A Samurai at Last
You can see the conflict between what he represents and the traditions he's upending when he strikes out on his own to capture one of the bandit's rifles. He's everything you want a samurai to be: brave, clever, a little bit sneaky and ultimately victorious. And yet when he gets back to the village with the gun, Kambei treats him like a teenager who broke curfew. And this after Kyuzo went out and did the exact same thing.
Kikuchiyo doesn't understand why, and you can feel his pain when Kambei gives him the third degree. The difference, for those keeping score at home, is that Kyuzo did it after telling Kambei that he would as part of a larger strategy, while Kikuchiyo just decided to do it on the spur of the moment. As a result, a key defense was left unmanned and the bandits killed some of the farmers. It's a tough lesson to learn, proving to him that while he may not be a farmer, he still has a long way to go before he's a samurai.
But his outlook carries good things as well as bad ones. For starters, he helps the samurai understand the peasants they're defending a lot better. Oh sure, he jumps all over the farmers early on and really doesn't seem to like them much. ("hey you, stop chewing your cud," he tells one of them at one point.) But when the other six cast dark doubts on the village when they learn it holds weapons from samurai the farmers have killed, Kikuchiyo gets up in their face with a little "you don't understand" action. Peasants have no protection from anyone, he argues. Samurai harass them, bandits harass them, and that's not even counting the monsoons or natural disasters that could take away their crops in one fell swoop. The farmers do what they have to do to survive… just like the samurai themselves are doing.
As a result, the samurai put themselves in the farmers' shoes a little more readily, and come to appreciate the hardships these simple folk have to face. In other words, Kikuchiyo links these two castes together, showing them common purpose and helping them work together in the face of a pretty big threat. Time once was, samurai and peasants never rubbed shoulders, which meant they never would have communicated properly and the bandits probably would have run roughshod over the whole village. It takes Kikuchiyo's individuality—and the courage to buck prevailing social trends—to make that happen.
In the movie's eyes, that makes him a samurai, regardless of whether the rest of society recognizes it or not. We see it when he's buried next to the other three fallen samurai at the end, but more importantly, we see it in his heroic final act: killing the leader of the bandits. It's more than just a good guy getting a bad guy. It's a validation of everything this guy wants to be.
The code of bushido states that even if a samurai has his head cut off, he should still be able to perform one final act. Kikuchiyo gets it in the end when the bandit leader shoots him… but he still stays on his feet and cuts the guy down, defeating the bandits at last and bringing the battle to a successful conclusion. That's the textbook definition of what a samurai should be. Kikuchiyo quite literally faked it 'til he made it, and got to die as the hero he fought so hard to become.