Masumi Shirase serves as a special investigator within the Cabinet Office, tasked with overseeing a video game realm engineered to mend strained parent-child bonds. Operating as a game administrator, she frequently materializes as non-playable characters bearing her name, steering protagonists through quests with calculated guidance.

In reality, she projects professionalism through a crisp black suit and government-issued ID. Her in-game avatar adopts the guise of a nun, perpetually stationed inside a stark black coffin—a visual gag recurring throughout her appearances. She wields the "Administrator Intervention" ability (colloquially dubbed "Account Ban" or "Akaban"), enabling her to rewrite game mechanics and orchestrate scenarios despite her non-combatant role.

A childhood marred by bullying over her distinctive name forged her resolve to reclaim it as a core identity. Now a single mother to a five-year-old daughter, her drive to repair fractured family ties directly informs her career, notably influencing her selection of beta tester Masato Oosuki due to his lineage linking to Hayato, a shadow from her past.

Notable exploits include a clumsily comedic housework showdown in Volume 4, underscoring her domestic ineptitude, and a brief stint as an idol in Volume 8 to thwart a global crisis. During the narrative’s climax, she supervises pivotal trials dissecting familial bonds, unmasking her meticulous stewardship of the game’s core mission.

Though maintaining formal boundaries, her interactions betray a latent investment in resolving interpersonal strife. While abstaining from direct party involvement, her strategic interjections—like neutralizing cheating guardians or mediating reconciliations—repeatedly alter the story’s course. Her arc traces a journey from childhood vulnerability to composed authority, blending bureaucratic precision with understated compassion, all anchored by her evolution into a confident architect of relational healing.