Jikū, also known as Jikū Acarya, is a supporting character in the anime and manga series The Peacock King. He holds the vital role of master and mentor to the series' protagonist, a young monk named Kujaku. As an elder priest within the secret demon-hunting organization known as Ura-Kōya, Jikū is entrusted with considerable wisdom and extensive spiritual knowledge, which he uses to guide his young disciple in harnessing supernatural abilities and confronting various occult threats. His position is one of significant responsibility, as he was entrusted with Kujaku's care by the boy's own father, a testament to the deep trust placed in him.

In terms of personality, Jikū is not portrayed as a one-dimensional or purely stoic master. His character is given complexity through a set of personal flaws that often mirror the less disciplined traits of his student, Kujaku. The character exhibits behaviors such as alcoholism and a tendency toward perversion, which serve to ground him and add an unconventional layer to his role as a spiritual guide. This combination of deep wisdom and human weakness makes him a more nuanced figure than a typical mentor archetype. His leadership within Ura-Kōya also positions him as a strategic figure, actively opposing the series' antagonistic forces, including the Rikudoshu and the Teachers of Eight Leaves, who seek to revive dark entities to bring about catastrophic events.

Jikū's background is intimately connected to Kujaku's family history. His knowledge of Kujaku's father underscores his protective role and contextualizes his unwavering commitment to preparing Kujaku for a challenging destiny. This relationship is a consistent element across various adaptations of the story. Whether in the original OVA series or the live-action films, Jikū maintains his fundamental position as Kujaku's master and instructor, with his narrative purpose remaining focused on guiding the protagonist and imparting essential knowledge. In some adaptations, such as the later OVA series, his involvement expands to include coordinating with international allies like Tibetan lamas and Chinese spiritualists to confront modern threats, demonstrating the broad scope of his responsibilities.

The character's journey reaches a definitive and impactful conclusion within the original manga continuity. Jikū is killed by the demon Hōō, a pivotal event that marks a significant turning point in the narrative and highlights the immense personal risks inherent in the ongoing battle against supernatural evils. This death serves as a major narrative beat, emphasizing the high stakes of the conflict that Kujaku must face. Overall, Jikū stands as a classic mentor figure, whose wisdom, strategic importance, and personal flaws provide a solid foundation for the protagonist's growth and the unfolding of the story's central conflicts.