Jim is the main protagonist of the 1978 anime series Treasure Island. In this adaptation, he is depicted as a 13-year-old boy with an energetic and kind-hearted nature. He lives with his mother and helps run the Admiral Benbow Inn, as his father, who was a sailor, has passed away from an illness while at sea. From a young age, Jim has harbored a desire to become a sailor like his father, and this personal dream serves as a significant motivator for his decision to join the expedition for Captain Flint's legendary treasure. A notable feature of this version of the character is his constant companion, a pet leopard or cheetah cub named Benbow, which highlights his youthful and adventurous spirit.

Jim's personality is marked by his courage, curiosity, and a strong sense of empathy. He is generally a dutiful and well-meaning young man who often prioritizes the well-being of his crewmates over the pursuit of gold, tending to their injuries and valuing their lives. His naivety is a key trait at the start of the story, making him trusting and willing to see the good in others. This is most prominently displayed in his initial relationship with the charismatic Long John Silver, whom he greatly admires and views as a best friend and father figure. The revelation of Silver's true nature as a ruthless pirate who was once Flint's right-hand man is a profound betrayal that forces Jim to confront a much harsher reality. Throughout the series, Jim struggles with a complex mix of emotions towards Silver, often responding with anger to mask his deep confusion and the hurt of the betrayal, yet he can never truly bring himself to hate the man completely. A crucial turning point in his emotional journey is the death of Redruth, an event that forces him to mature rapidly and face the world more realistically.

Jim's most significant relationship is with Long John Silver, which evolves from affectionate mentorship to a tense and complicated rivalry. Silver continues to regard Jim as a friend even after his mutiny, creating a central emotional conflict for the boy. Jim also forms strong bonds with the loyal crew of the Hispaniola, including Dr. Livesey, from whom he learns lessons of ethics and courage. His innate kindness and brave actions earn him the trust of others, even among his rivals, and he eventually marries his childhood sweetheart, Lilly, living prosperously after the adventure. While not possessing supernatural powers, Jim's notable abilities include his resourcefulness, growing intelligence, and unwavering courage in the face of danger. His impulsive nature sometimes gets him into trouble, but it is often his quick thinking and determination that help him and his friends survive the many perils on Treasure Island.