Saki Nikaido led the Kyushu biker gang Dorami until her death at 18 in 1997, fatally crashing during a motorcycle race against rivals due to her relentless drive to win. Shaped by childhood isolation and fragility, she cultivated a rebellious persona, channeling her defiance into building Dorami after a transformative radio broadcast by motivational figure White Ryu. Alongside best friend Reiko Amabuki, she dominated Kyushu’s biker scene, balancing her hardened exterior with a secret fondness for Tamagotchi devices—though neglect often left her with comically mismatched "Oyajitchi" results.

Revived as a zombie, she spearheaded the idol group Franchouchou as "The Legendary Chief Biker," clashing initially with member Sakura Minamoto over perceived weakness. Their rivalry dissolved after a rap battle showcased Sakura’s tenacity, forging mutual respect. Saki gradually transitioned from lone rebel to unifying leader, subordinating her pride to the group’s mission. Her undead physiology granted heightened durability, detachable limbs, and agelessness, surviving explosions and collisions that mirrored her mortal end. Retaining combat prowess from her biker days, she strategized defenses and dismantled threats, even toppling adversaries twice her size.

A reunion with White Ryu exposed unresolved vulnerabilities when he spurned her affections, citing her static existence as a zombie. This rejection deepened her awareness of immortality’s burdens, yet she redirected her resolve into rallying others—consoling Ai Mizuno through grief and galvanizing Saga’s citizens post-disaster via a benefit concert. Her leadership fused blunt force with understated empathy, adapting her lone-wolf instincts to collaborative idol dynamics. She backed Sakura’s stabilizing efforts and engaged earnestly in radio campaigns to revive Saga, embodying a duality: the untamed biker legacy tempered by loyalty to her second life’s purpose.