Yoko Ryuuzaki, full name 竜崎 陽子, hails from Yokohama and belongs to an extremely wealthy family. Her background includes German noble ancestry through her grandmother, with controversial rumored lineage connecting her to Adolf Hitler as a descendant; this influences her strong personal sense of justice and preference for period dramas centered on punishing evil.

She presents as a bespectacled student typically transported by limousine. Her defining skill is masterful disguise, enabling flawless impersonation of individuals across all ages, genders, and nationalities. This extends to vocal mimicry, replicating voices accurately from memory alone. Her comprehensive transformation abilities allow her to adopt even the physical appearance and voice of a middle-aged male police officer during operations.

As a detective group member, she collaborates to counter threats, tactically employing her disguise expertise during confrontations. Her talent proves instrumental in executing coordinated strategies against adversaries like mercenary attackers. Personality-wise, she displays a reserved default demeanor, contrasting with confident versatility when adopting other identities.