Manon Libelle, daughter of Count Libelle and a Lost One known as Countess Libelle, witnessed her mother's murder by Flare during her childhood. Her mother, summoned through magecraft, had refused to use her Pure Concept to prevent uncontrollable escalation. Manon pleaded for her own death during the attack. Flare's revelation that Pure Concepts could not be inherited caused The Fourth secret organization to scorn and denigrate Manon for lacking power. Years of mockery cultivated a deep-seated resentment within Manon. She resolved to become "taboo," embracing others' worst expectations. This drove her to join the subversive group The Fourth, who considered themselves a liberated social class. Manon publicly maintained a facade of kindness, gentleness, and naive mildness, while privately indulging in sadism and violence. Manon forged a significant alliance with Pandæmonium, a centuries-old Lost One whose Pure Concept of [Chaos] caused one of the Four Major Human Errors. Appearing as a will-less child, Pandæmonium provided blood Manon used to manufacture the destructive drug monstrine. Manon distributed this drug through The Fourth, leveraging Pandæmonium's powers to fuel societal disruption. She acted as an older sister figure to Pandæmonium despite exploiting her destructively. Manon's efforts culminated in a confrontation where she attempted to wield forbidden powers to defeat adversaries. This act resulted in her gruesome demise as Pandæmonium's essence consumed and replaced her body during the battle.