Vivi Holopainen operates as a lethal assassin in the Gillette Corps, a division of the Post-war Reconstruction Implementation Agency. Specializing in pinpoint needle-throwing techniques—capable of striking targets as small as distant coins—she later diversifies her skills with martial arts and swordsmanship across evolving missions.

Her initial peach-blonde hair and blue eyes shift dramatically after pivotal events: first to white-silver hair and Chaika-like purple eyes following the disappearance of her unrequited love, commander Albéric Gillette. Later enhancements by ally Nikolay Autotor deepen her hair and eyes to dark purple, mirroring her growing ties to the Chaika legacy. These transformations stem from her incomplete clone origins, engineered from Emperor Arthur Gaz’s genetics but never fully realized.

An orphan shaped by loyalty to the Gillette Corps, Vivi balances hardened resolve with concealed vulnerability, particularly around comrades Zita Brusasco and Nikolay. Albéric’s presumed death fractures her emotional stability, fueling near-breakdowns yet sharpening her resolve to adhere to personal ethics amid chaos.

Revelations of her "half-Chaika" status cement her genetic connection to the Gaz Empire, contextualizing her evolving abilities without eroding her core identity. Her narrative intertwines relentless pursuit of Albéric’s validation with dual roles as covert operative and frontline combatant, anchoring her within the Corps’ high-stakes operations.