Chapra enters life as a Shudra caste slave in ancient India, enduring harsh conditions and poverty alongside his mother. A pivotal encounter with Tatta, a pariah boy gifted with the supernatural ability to transfer his consciousness into animals, alters his path. Tatta prevents Chapra's mother from being sold, forging a bond between the boys. Together, they plot revenge against the Kosala army for destroying Tatta's village and killing his family. Chapra abandons this plan when a chance arises to elevate his status. He rescues General Budai of Kosala after a battle, falsely presenting himself as a Kshatriya orphan. Impressed, General Budai adopts him, enabling Chapra to conceal his slave origins and ascend within Kosala's military ranks. His driving motivation remains securing a better life for his mother and using his newfound status for protection.

As General Budai's adopted son, Chapra trains intensely and displays exceptional battlefield bravery. He rises to become a commander, eventually leading Kosala's military campaigns. His strategic brilliance earns him recognition as one of Kosala's most formidable warriors. This position brings him into direct conflict with the Shakya kingdom, particularly during Kosala's invasion. Chapra commands Kosala's forces against Prince Siddhartha, who leads Shakya's defense. Their confrontation embodies a clash of ideologies—Chapra's ambition for power and status versus Siddhartha's rejection of violence and caste. Despite his military success, Chapra's fabricated background remains a vulnerability. His biological mother reappears and publicly reveals his Shudra origins, shattering his position and leading to rejection by Kosala's elite. Facing disgrace and persecution, Chapra attempts to flee with his mother. They are pursued and killed by Kosalan soldiers.

In Osamu Tezuka's original manga, Chapra's story unfolds primarily during Siddhartha's childhood, concluding with his death while Siddhartha is young. The manga includes a direct adult encounter between Chapra and Tatta. The anime adaptation condenses events from the manga's first two volumes, altering timelines. While Siddhartha ages from infancy to adulthood in the film, Chapra and his mother appear not to age significantly during the same period. The film amplifies emotional elements, particularly Chapra's relationship with the bandit girl Migaila and their forced separation. Both versions consistently frame Chapra as a symbol of ambition thwarted by societal inequities, with his death serving as a catalyst for themes of suffering and caste oppression.