Lune, a horned devil from hell, operates as an executive within the demon organization Vintage and the Runaway Spirit Squad. Her striking appearance blends youthful and macabre elements: a middle school sailor uniform layered under a lab coat, long hair with precise bangs, twin horns, and bandages winding across her right arm, legs, and hands, punctuated by band-aids on her left shin and fingers. She carries a hagoromo, a handbag fitted with a skull sensor, and wields a box cutter—both tool and weapon.

Masochistic and indolent, she revels in sweets like taiyaki and sugary coffee, punctuating her lethargy with abrupt acts of self-harm, such as stabbing her own hand to unsettle others. Routine tasks, like Vintage’s roll calls, bore her; authority is a mantle she wears reluctantly after replacing Haqua as District Chief. Tasked with hunting goddesses hidden among Keima Katsuragi’s past conquests, she devises a plan to ambush all twelve targets at once, bypassing tedious legwork.

Her schemes blend psychological cunning and physical theatrics: planting a tracker on Ayumi Takahara during the Eve of Mai-High festival, carving an "X" into Keima’s door as a taunt, and manipulating the emotional fractures of possessed girls. She clashes with Haqua, leveraging her rank with icy pragmatism, yet impulsively scans Ayumi with her skull sensor—a move that initially yields nothing. Coordinating Vintage agents to monitor signals from the possessed, she balances strategic patience with irritation at delays.

From intimidating delinquents through bloody displays to orchestrating mass captures under night’s cover, Lune evolves from a solitary provocateur to a systemic threat. In her final maneuver, she reclines on a moonlit bench, speculating if goddesses masquerade as runaway spirits, then triggers a synchronized strike—cementing her role as Vintage’s relentless adversary, threading chaos through Keima’s world with methodical, sugar-fueled malice.