Shinigami Oyabin, a grim reaper over two millennia old, exists as a spectral floating skull after shedding his once-handsome physical form. Tasked with mentoring fledgling reapers, he enforces discipline through harsh methods like dripping hot candle wax and wielding whips to rectify errors. Though stern, he harbors an unexpected fondness for anime, frequently procuring DVDs during human-world visits.

In alternate narratives, he partners with fellow reaper Misaki, offering guidance tinged with lecherous humor. Spin-offs expand his lore, revealing a daughter whose life inspired Mina—a character within an in-universe video game treated as a prophetic text by reapers. Oyabin confirms the game mirrors his daughter’s experiences, embedding it as a meta-narrative cornerstone. His duties involve disclosing imminent deaths to humans and detailing esoteric rituals—often involving supernatural reproduction—to temporarily evade fate.

Historically revered for charisma, he now operates as a detached overseer within the reaper hierarchy, enforcing protocols across timelines. His authority spans training initiates and mediating human-reaper interactions, executed with a blend of macabre wit and pragmatic efficiency. Multiversal accounts depict him navigating alternate realities, perpetually balancing mentorship with the grim mechanics of mortality.