Idia is a tall young man with pale skin and bright blue, fire-like hair. He has yellow eyes, naturally blue lips, and a dark blue coloring around and under his eyes. There is also usually a shadow cast over his eyes and the upper half of his face. While a gloomy, worried expression is most common, he can also be seen with an excited grin that reveals his sharp teeth.

Idia’s hair is considerably long and reaches down to his knees. While his long bangs fall loosely around his face and between his eyes, the hair on the top of his head seems to flow upwards. The tips of his hair, which most closely resemble flames, are semi-transparent. On some occasions, the color of Idia’s hair changes to reflect his mood. When he is relaxed, his flaming hair stays a soothing blue, but when he's enraged, it turns a vivid red-orange. Additionally, his hair tips can turn pink whenever he feels embarrassed. Idia is intensely introverted, cynical, analytical, imaginative, excitable, and self-conscious. He strongly prefers controlling the distance between himself and other people, and ordinary face-to-face social situations can make him hesitant, defensive, or eager to escape. Crowds and public attention are treated almost like physical hazards: simply going into town is described in gaming language as rapidly draining his “HP and MP.”

His withdrawn presentation contrasts dramatically with how animated he becomes around his interests. Games, technology, idols, magical engineering, and other “nerdy” subjects can immediately transform his speech into rapid, enthusiastic monologues full of specialized terminology and elaborate analogies. He may struggle to sustain ordinary small talk yet become extremely expressive once a subject enters a domain he understands and values.