L'Oreille, a high-ranking member of the Oración Seis, belongs to an elite cadre of Advanced Replicants engineered by the sorcerer Magus Diluculum to dominate Felicidad’s continents. She rules Sonrisa, a realm adorned with East Asian-inspired spires and perpetual cherry blossoms—a serene veneer concealing the iron grip of her tyranny. Though outwardly composed and regal, her tranquil facade obscures a haunting obsession: an insatiable hunger to spread fear and despair.

Her signature power, bestowed by Diluculum himself, allows her to consume monster souls and metamorphose into a spectral Reaper. This ability fuels her orchestration of the Harvest Festival, a cataclysmic ritual that strips entire continents of life, as seen in her annihilation of Nadeyat'sya. A master strategist, she manipulates allies and enemies alike, first collaborating with Glaza before betraying him alongside Zanas to seize his grimoire. Following Glaza’s downfall, she independently activates the Harvest Festival, seeking to hoard enough power to rival deities.

Diluculum’s resurrection later exposes her unwavering loyalty; spared the grotesque demi-beast fate of her fellow Oración Seis, she remains his willing lieutenant. Together, they pursue the Grand Harvest Festival—a global soul harvest meant to usurp celestial powers. Her reign concludes only when Ten’s coalition defeats her, dismantling both her ambitions and Diluculum’s apocalyptic designs.

Implanted into the world as an infant, L'Oreille was cultivated through Diluculum’s selective trials to identify candidates of exceptional potential. Shaped by calculated neglect and devoid of moral guidance, her upbringing forged a ruler who equates cruelty with efficiency, aligning seamlessly with her creator’s goal of harvesting mortal souls to defy the divine order.