Ermalit de Blanchefort, known as Eru, is a French individual with blonde hair, blue eyes, and a height of 1.66 meters. Her figure measures 88-58-86. She consistently appears in a school uniform paired with a skirt and pantyhose.

Her history includes a resolved internal struggle against a being that claimed to be part of her, a conflict settled through Wataru's intervention. This led her to declare him her partner, demanding his absolute loyalty and undivided focus. Their bond develops romantically, with Ermalit initiating physical intimacy in any setting. During these encounters, she assumes a dominant position, dictating activities to suit her preferences, though arousal reveals a more vulnerable side.

Within her story's context, Ermalit belongs to a group aiding Wataru in generating energy through sexual acts to oppose the enemy organization "4D." She embodies the tsundere archetype, often presenting a cold or harsh exterior that conceals inner fragility. Her emotional complexity surfaces through fleeting tenderness and psychological turmoil stemming from past trauma. Gradually, she lowers her defensive walls to express sincere affection for Wataru.