With long black hair and deep red eyes, Maki emerged from Hollow House, an assassin training institute where her childhood forged an aggressive streak. Sold afterward to a Russian crime syndicate, she served as a contract killer and bagman. Her personality blends wariness and a quick temper with unexpected naivety beneath a hardened exterior. Rebellious by nature, she frequently rides a Suzuki GSX-R motorcycle, channeling her love for speed—though her original blue Suzuki Hayabusa 1300 was destroyed during a chase with Rena in her first SORD confrontation. She treasures an old Swiss watch above all other possessions.

In combat, Maki wields four Glock 26 pistols, leveraging her strong, well-built physique for lethal efficiency. Before joining SORD, she habitually abused her firearms. After Volume 2, she became a SORD member specializing in firearms alongside Rena. Her relationships include a complex history with Rena Fukami predating Hollow House; though independently smarter than Rena, their shared past colors their interactions. She holds deep respect for Yamamoto and bonds with Rei over their mutual passion for motorcycles.

Operating within Mihama Academy’s elite Class A unit under SORD, Maki participates in high-risk missions against national threats. In Volume 8, she joins the final assault on the cult "The Fatal Answer" (TFA). Mission outcomes diverge: without critical support, she dies alongside Chris and Rena in the bad ending, while the good ending sees all Class A members survive. Her development involves recovering from prior injuries and refining combat skills. While her long-term fate ties to branching endings, she remains integral to SORD’s operations.