Jikū Ajari mentors the protagonist Kujaku, entrusted with his care by Kujaku's father. As an elder monk in the secret demon-hunting organization Ura-Kōya, he commands considerable wisdom and spiritual knowledge. Despite his respected status, he displays contrasting traits like alcoholism and perverted tendencies. His guidance proves instrumental in Kujaku's development as an exorcist facing supernatural threats.

The character maintains this role consistently across adaptations. He appears in both the original 1988-1991 OVA series and the 1994 OVA revival directed by Rintaro. In the latter, he aids Kujaku's fight against a Neo-Nazi faction seeking the Dragon Orb artifact to unleash dark forces. His background consistently emphasizes his long-standing guardianship of Kujaku and connection to the protagonist's family history. Live-action film adaptations also feature the character, portrayed by actors including Ken Ogata and Shintaro Katsu, while his core attributes and narrative function remain unchanged.