"Shōnen Tokugawa Ieyasu" chronicles the early life of Tokugawa Ieyasu, a pivotal figure in Japanese history who would later become the founder of the Tokugawa shogunate. The series begins with Ieyasu's childhood, when he was known as Takechiyo, a hostage of the Imagawa clan following his father's defeat in battle. This period of his life is marked by hardship and political maneuvering, as he navigates the complex dynamics of feudal Japan. The narrative highlights his resilience and strategic thinking, traits that would define his future leadership.

As Ieyasu grows older, the story delves into his alliances and rivalries with other key historical figures, such as Oda Nobunaga and Toyotomi Hideyoshi. The series portrays his rise from a minor daimyo to a powerful warlord, emphasizing his ability to adapt and survive in a turbulent era. Key events, such as the Battle of Okehazama and the formation of the Tokugawa clan's power base, are depicted with attention to historical context and character development.

The anime also explores Ieyasu's personal relationships, including his bond with his retainers and family, as well as his struggles with trust and loyalty in a world dominated by betrayal. The narrative balances political intrigue with moments of introspection, offering a multifaceted portrayal of Ieyasu's journey from a vulnerable child to a shrewd and determined leader. Through its depiction of his formative years, the series provides insight into the qualities that enabled him to unify Japan and establish a lasting legacy.