Set in 1543, the movie starts with two ronin plotting to get a position with a noble. One attacks Takeda Shingen, and the other, Kansuke Yamamoto (Toshiro Mifune) goes in to the rescue. Kansuke then betrays his partner, killing him in the duel. Kansuke, the ruthless opportunist, then gets a job working for Takeda. He vows to make Lord Takeda of Kai, the mightiest lord in the nation.
Takeda is looking to unite the land, and looks to first invade Suwa. Kansuke is soon recognized for having a head for strategy and is promoted and given his own men. Takeda advances on Suwa Castle with 20,000 men. Kansuke suggests they negotiate a surrender rather than attack and he is sent as the messenger to negotiate. Lord Harunobu of Suwa then visits Takeda three times. Kansuke convinces him that this is because Harunobu wants Takeda to make a return visit, where he will be assassinated. He convinces him to kill Harunobu first which he does.
Takeda's forces take Suwa and Princess Yu refuses to kill herself. Kansuke is taken with her and then she becomes Takeda's concubine. She soon has a son with him, Katsuyori. Kansuke is clearly in love with her and will do anything for her and her son. He has a plan to conquer the whole country so that when Katsuyori comes of age he will rule it all. When Kansuke takes her back to Suwa, so she and Katsutori can be protected from plots from Tanaka's first wife and children, she refuses to go. She loves Takeda, the father of her child, but she also hates him, the murderer of her father.
Nobukato, one of Takeda's generals has his men paint their armor red and carry red banners. His troops are really strong, particularly at the start of a battle. There are some great battle scenes with archers on horseback and soldiers with ten foot swords as Kansuke tries to carry out his plan. When Nobukato gets killed in battle, Kansuke is devastated. Kansuke decides to take the life of Takeda's wife, so Princess Yu and her child will be safe. Then Kansuke and Takeda become monks, to protect Takeda's family legacy and Katsuyori's inheritance.
The final battle is with the Echigo army, their strongest opponents. Kansuke devises a flanking strategy that he hopes will trap the enemy forces. As the battle starts and the Echigo men attack, Kansuke things his strategy is fatally flawed. Kansuke then leads a charge to try to delay the enemy until their main troops arrive. Kansuke takes an arrow to the eye but lives long enough to see his main force arrive for the victory.
A beautifully filmed movie based on historical characters and directed by Hiroshi Inagaki who had done the "Samurai Trilogy" and it starred the grat Toshiro Mifune. Why wasn't is one of the greats? It was very good but the story was a little unfocused. It was about Takeda trying to conquer the country but we saw it through the eyes of Kansuke and he wasn't the easiest guy in the world to cheer for. At 165 minutes the movie dragged at points and was a little hard to follow. The romance between Kansuke and Lady Yu seemed forced and added little to the story. But overall a good samurai movie.