Mizuka Sonohara, dubbed the Ace of Pursuit, is a genetically engineered human whose aging ceased at 16 despite her 300-year lifespan, a result of alterations from Schmerman’s genes that eliminated her need for sustenance. As an Ace, she ranks among elite soldiers whose unique powers correlate to their "Count"—a numerical manifestation of their core identity. Her Count of 32,000 embodies relentless persistence, fueling combat prowess that intensifies with her resolve.

Trained at the 13th Special Military Forces School, she was reshaped by the Aerial Ace Project, a military initiative infusing Schmerman’s DNA to forge immortal super-soldiers. The modifications granted her immortality, heightened strength, and the capacity to launch homing projectiles that bypass barriers to strike targets. Her arsenal includes jetpack-assisted flight, supersonic-speed firearms, and city-block-level destructive output.

Though designated a frontline Ace in the Abandonment War, strategic commander Licht Bach diverted her from direct combat to preserve her oath against killing, relegating her to support roles. Subsequent genetic enhancements later surged her Count and combat efficiency, enabling her to endure assaults from adversaries augmented by Schmerman’s modifications.

A defining trial arose when she spearheaded a mission to reclaim a stolen ballot, overcoming psychological coercion and physical traps. This success marked her evolution from an uncertain recruit to a dependable operative capable of autonomous decisions. Partnerships with allies such as Pele Popolo reinforced her strategic value, with her tenacity proving pivotal in critical battles.

Her appearance—brown eyes, black hip-length hair often tied in a ponytail, a prosthetic arm, glasses, and military-styled attire—complements her role as a precision-focused gunslinger. Once characterized by timidity, her arc culminates in steadfast resilience, navigating warfare’s moral ambiguities while adhering to non-lethal methods aligned with her principles.