I watched this film because I was curious about Sengoku period of Japan. Moreover, the film from Akira Kurosawa were so philosophical.
According to the introduction of Kagemusha film: "Akira Kurosawa's lauded feudal epic presents the tale of a petty thief (Tatsuya Nakadai) who is recruited to impersonate Shingen (also Nakadai), an aging warlord, in order to avoid attacks by competing clans. When Shingen dies, his generals reluctantly agree to have the impostor take over as the powerful ruler. He soon begins to appreciate life as Shingen, but his commitment to the role is tested when he must lead his troops into battle against the forces of a rival warlord."
This introduction was brief but cover most of the story. I wondered how a people can pretend to be another important man and then turned to be that man. This sounds like a child grow up and do the way their parents did. I feel so touched by the thief finally died for his belief, that he had already be Shingen at the end of the film, not a shadow any more. His soul grew up and he was not a humble thief anymore. I believe that as a ordinary people, we can learn from the store somehow that we can be a great man eventually after we experience the soul journey and then grow up.