Kazuomi Sakaki is an adult male with blonde hair and black eyes, typically dressed in suits reflecting his professional demeanor. He possesses the unique ability to see and communicate with ghosts, a trait leading to societal ostracization and isolation. Significant but unspecified trauma in his past contributes to his emotional reserve and reluctance to share personal feelings.

Initially serving as a bodyguard for the teenage necromancer Erika Hiura, Sakaki's role extends beyond mere protection. He exhibits profound loyalty and care for Erika, actively wishing to rescue her from manipulative circumstances, encapsulated in his plea: "If you're going to escape, take me with you." This protective instinct drives his involvement in supernatural cases alongside other main characters, though his live-action film appearances were limited.

A pivotal transformation occurs when Erika saves his life, granting Sakaki a "deathless" bodily constitution. Supernatural attacks pass harmlessly through him, revealing this immortality-like trait. He utilizes this ability during confrontations, aiding protagonists against antagonistic forces.

Sakaki's personality blends stoicism with underlying compassion. He maintains a reserved and serious demeanor in his duties yet shows genuine concern for others' well-being. His interactions, especially with Erika, reveal a capacity for empathy despite his guarded nature. While not central to all narrative arcs, his involvement grows in later segments of the anime and manga, where he assists in resolving supernatural conflicts.