Japan was a very restrictive culture in terms of class and caste. You didn't get to rise through the ranks to become an aristocrat. Farmers were farmers, samurai were samurai, and the family you were born into pretty much determined what you would do with your whole darn life.
But there's a twist to it. In the era of Seven Samurai, those walls were starting to crack a bit. Samurai had to do peasant-like things to survive and peasants could pass themselves off as samurai if no one squinted at them too hard. The characters in this movie not only have to deal with the limitations of their class, but with what happens when those safe, dependable boundaries suddenly become a lot less dependable.
Questions About Society and Class
How do each of the characters embody the class they're supposed to come from? How do they go against the grain?
How do tasks or duties define each character's class here? What does it say when they take on tasks that are above or beneath them?
What outward trappings help define a character's class? And at what points do those trappings give the wrong impression about a character's class?
How many in-film conflicts arise between characters of a different class? Which ones are they?
Chew on This
You need to fight if you want to keep the privileges of your class, or rise above it.
Your class is your class no matter what, and there's nothing to do to change that.