Akira Seno is a shinigami, a grim reaper tasked with guiding souls to the afterlife. He confronts Makoto Nakazono, a high school student capable of seeing reapers who has always maintained a passive stance. Akira directly questions Makoto's non-interference, specifically revealing his assignment: Makoto's best friend, Hazuki Horiuchi. This encounter forces Makoto to reconsider his passive stance, acting as the catalyst for his actions despite the typical immutability of reapers' operations.

Akira works among a collective of reapers including Ichiko Shimura, Kenji Izumi, and Shinobu Toujou. Identified as an "Agent of the Afterlife," he wields a scythe consistent with his role. His demeanor during the confrontation with Makoto is interrogative and confrontational, embodying the reapers' detachment from human emotion while enforcing death's inevitability. His narrative function centers on his identity as a supernatural entity challenging the protagonist's resignation to fate.