Chiaki delivers shigofumi—letters sent by the deceased to the living—as a coworker and supervisor to Fumika. Having perished in a car accident over fifty years ago, she remains frozen in the youthful guise of a petite girl, a stark contrast to Fumika’s aging physique, which underscores Fumika’s lingering ties to the living world.

Exuding emotional expressiveness, Chiaki frequently displays frustration, cheerfulness, or playful mischief. She approaches her duties with a relaxed pragmatism, sometimes sidestepping challenging deliveries by falsifying addresses, prioritizing efficiency over rigid protocol. Her encounters with Fumika unfold mostly in Shigo, the afterlife realm, as their earthly routes seldom intersect.

Her work is aided by Matoma, a staff housing an artificial intelligence with a monotone male voice, which streamlines task management and delivery tracking. Matoma’s precision and stern demeanor clash with the flaws of Fumika’s staff, Kanaka, sparking intermittent tension between the tools. Though Chiaki maintains a businesslike rapport with Matoma, she occasionally jests at Kanaka’s shortcomings.

Chiaki died in her early twenties, her precise age unrecorded, and has since spent decades as a shigofumi carrier. Despite her childlike appearance, she partakes in adult indulgences like drinking. While her motivations for persisting in the role remain unexamined, her enduring tenure implies either resigned compliance or an absence of other purpose.