PLOT WARNING CONTAINS SPOILERS
story begins with nine young samurai, who are worried about corruption in the leadership of their clan. Although they know of two elders who are "bad," the youths misjudge who the real mastermind behind these two is, and end up asking that wrong one for help. As the nine meet secretly at a temple and discuss their problem, a ronin (Mifune) suddenly appears from another room. The ronin explains the stupidity and naiveté of their conclusions and decides to help them.
The plot then unfolds as he tries to outwit the three evil elders and their minions, with the young samurai constantly ruining his plans. Despite evidence to the contrary, some of them continue to regard the ronin as a problem figure: he has bad manners, behavior unbecoming a samurai, weird ways to express his thoughts, and bizarre attitude to violence. He obviously has no compunction killing people, often unnecessarily.
A key objective is the rescue of Mutsuta, an honest official, and his family. Mutsuta's wife (played by Takao Irie) is rescued early on, but remains strangely oblivious to the danger around her, and maintains a cheery civility in comic contrast to the tension of the young samurai. She asks the ronin's name; looking out the window at tsubaki (camellia) trees, he invents the name Tsubaki Sanjr (from sanj 'thirty', because he always aks for thirty ryo). The lady insists as if advising him on table manners that Mr Tsubaki refrain from unnecessary killing. The lady shows insight when she compares Sanjuro to a "glittering sword" and remarks that "the best sword stays in its scabbard."
The nine young samurai begin as innocent idealistic greenhorns who judge on appearances, are easily duped by a more experienced elder, and are quick to stumble into danger without even knowing what they are doing. They end wiser: they have learned the virtues of patience.
The famous final scene of his duel with Hanbei, the henchman of the corrupt superintendent, is poignant. Throughout the story, Sanjuro poses as a bad ronin who is after making a quick score. He is so convincing that Hanbei (Tatsuya Nakadai) swallows his line and becomes the unwitting accomplice of his own demise. He cannot stand being made a fool and challenges Sanjuro to a duel. Sanjuro is reluctant to fight and tries to dissuade Hanbei saying that if they do fight, one of them would die and there is nothing to be gained from that.
Hanbei insists and the two face each other. And then, in a flash, it's over: a fountain of blood gushes from Hanbei and he slumps to the ground, lifeless. When the young samurai cheer his victory, Sanjuro becomes extremely agitated and angry at their naive insensitivity . In the most revealing remark, he states that dead adversary was exactly like him, so that at least he now has an understanding of what he really represents. Sanjuro then leaves towards an unspecified direction .
