This film could have been titled “There Will Be Beef.”
"Kagemusha" is a samurai drama by the director who most successfully introduced the genre to the West (with such classics as "The Seven Samurai" and "Yojimbo"), and who, at the age of seventy, made an epic that dares to wonder what meaning the samurai code -- or any human code -- really has in the life of an individual man. His film is basically the story of one such man, a common thief who, because of his astonishing resemblance to the warlord Shingen, is chosen as Shingen's double.
When Shingen is mortally wounded in battle, the great Takeda clan secretly replaces him with the double -- so their enemies will not learn that Shingen is dead. Thus begins a period of three years during which the kagemusha is treated by everyone, even his son and his mistresses, as if he were the real Shingen. Only his closest advisers know the truth.
But he is not Lord Shingen. And so every scene is undercut with irony. It is important that both friends and enemies believe Shin-gen is alive; his appearance, or shadow, creates both the respect of his clan and the caution of his enemies. If he is unmasked, he is useless; as Shingen's double, he can send hundreds of men to be killed, and his own guards will willingly sacrifice their lives for him. But as himself, he is worthless, and when he is unmasked, he's banished into the wilderness.
What is Kurosawa saying here? I suspect the answer can be found in a contrast between two kinds of scenes. His film contains epic battle scenes of astonishing beauty and scope. And then there are the intimate scenes in the throne room, the bedroom, the castles, and battlefield camps. The great battle scenes glorify the samurai system. Armies of thousands of men throw themselves heedlessly at death, for the sake of pride. But the intimate scenes undermine that glorious tradition; as everyone holds their breath, Shingen's double is tested in meetings with his son, his mistresses, and his horse. They know him best of all. If they are not fooled, all of the panoply and battlefield courage is meaningless, because the Takeda clan has lost the leader who is their figurehead; the illusion that he exists creates the clan's reality.