Ayumu Arakaki serves as a dedicated police officer patrolling Sorasaki’s bustling shopping district, upholding order with the same resolve instilled by her late mentor—Momo Minamoto’s father, a respected officer whose legacy she carries. This bond cements Ayumu as a guiding figure for Momo, fueling the younger woman’s determination to honor her father’s path by safeguarding their community.

Early in the series, Ayumu’s routine patrol through Ogimachi takes a perilous turn when she is abducted by operatives of the Moryo syndicate. Her disappearance acts as the spark that propels Momo into action, drawing her into the shadowy world of Tsukikage as she races to intervene. Ayumu’s ordeal starkly illustrates the dangers confronting Sorasaki’s law enforcement and amplifies the escalating clash between Tsukikage’s covert operations and Moryo’s criminal ambitions.