Jigo, also known as Jiko Bo, is a character who initially appears as a helpful and knowledgeable monk but is later revealed to be a hidden antagonist motivated by personal gain. He is short and round in the middle, which gives him an unthreatening appearance, yet he is portrayed as highly knowledgeable, greedy, humorous, and somewhat mysterious. A member of a secret organization called the Shisho-Ren that serves the Emperor and the royal court, Jigo operates under a royal charter to hunt the Forest Spirit. His primary motivation is to present the severed head of the Forest Spirit to the Emperor, as it is said to possess the power of eternal youth, in exchange for a substantial reward.

In his initial role in the story, Jigo encounters Ashitaka and provides him with information about the Forest Spirit while expressing a pessimistic view of the world. He is also the individual who sold Lady Eboshi the guns she used to defeat the boar god Nago. Later, he reveals he has permission from the Emperor to hunt the Forest Spirit and commands platoons of riflemen and specialized hunters. He convinces Lady Eboshi to help him slay the Forest Spirit by claiming she owes him for the use of his riflemen. Jigo orchestrates the hunt, deliberately letting Eboshi be the one to kill the god, as he believes it is best to let others do the work of killing gods. He then takes the severed head and attempts to flee the ensuing destruction.

Key relationships include his transactional alliance with Lady Eboshi, whom he manipulates for his own purposes, and his initial mentorship of Ashitaka, which turns into a confrontation when their goals conflict. Jigo represents a form of opportunistic ambition and a connection to the imperial court, which stands in contrast to the more local conflicts between Irontown and the forest. His development is less about personal change and more about the revelation of his true nature as a self-serving agent of the state. In the climax, confronted by Ashitaka and San and surrounded by the Forest Spirit's corrupting influence, he is left with no choice but to surrender the head, allowing the spirit to reclaim it and cease its destruction. The character has been noted by director Hayao Miyazaki to represent Japanese people, and details such as his offering of expensive miso soup and possession of luxury kitchenware imply he may have once been a member of the nobility.