Based on

Movies like The King and His Vassal (1981)

This is a story of "Takechiyo," the previous name of Iemitsu Tokunaga, the third Shogun (General). Takechiyo got sick of daily run-of-the-mill tasks, and it put him off being the Shogun, saying "there is no truth". Then, Hikozaemon Ookubo took him to Tasuke Isshin to bring him up into a full-fledged and admirable man.