|“||I'm positive that this will become a world where our peoples can live side by side, as friends!! We'll be able to understand each other!||”|
Lemiel is a young man with blond hair and green eyes.
Lemiel wears a double-breasted, long-sleeved, white jacket with a high, dark-colored collar. The jacket extends below his waist and is trimmed with gold. He wears two belts on top of it, and his grimoire pouch hangs off the back of his dark-colored belt. He also wears white pants, white stockings and black shoes. Over this, he hears a blue cape with white fur trim at his collar.
Lemiel is an eccentric young man, who is incredibly curious about magic. He also doesn't possess any prejudice towards commoners nor elves, unlike most human nobles. One of his goals was to create magical items that would benefit everyone, including those having little magical abilities.
One day, Lemiel and Licht save Tetia after she runs away from the castle and is caught in a magical tornado. The three become friends, and Lemiel wants to help bring elves and humans together.
On the day of the wedding, Lemiel is lured into the devil's trap in the castle. Secre releases him and they race to the wedding venue but arrive too late to stop the massacre. To prevent the devil taking his body, Licht turns himself into a giant demon.
Lemiel is forced to defend the kingdom from the monster and its attacks. When the monster focuses its magic into a single attack, Lemiel uses the magic siphon to absorb the magic. Although the magic tool breaks, it weakens Licht enough for Lemiel to slay the monster. During the fight, Lemiel is mortally wounded so Secre seals him in a statue atop the giant skull. He later becomes known as the first Magic Emperor.
Five centuries later, Secre and Finral Roulacase use the magic stones to awaken Lemiel. He launches all three of them toward the Shadow Palace and enters with Secre. After passing through the gate, they appear in the topmost chamber and confront the devil. Lemiel and Secre fly over to Licht, and Secre unseals Licht's soul, awakening his memory and personality. Licht thanks Lemiel for stopping him centuries ago. The three fly over to the platform where Asta, Yuno, and Patolli are.
The devil attacks the group, but Lemiel and Licht blast it back with Lamp of Avior Gloria and Origin Flash Barrage. The pair then attack the devil directly, flying around it and throwing swords of light. They are too fast for the devil, and Lemiel drives a sword through the devil's torso. However, the devil summons a demonic trident that shatters the sword and severs Lemiel's left arm. Before the devil can kill Lemiel, Asta blocks the weapon with his Anti Magic Weapon, which shocks Lemiel.
- Immense Magic Power: As a nobleman and the first Magic Emperor, Lemiel possesses an immense amount of magic power. His spells are capable of matching the attacks of Licht's demonic transformation. After using a magic tool to absorb Licht's monstrous magic, Lemiel's own magic is tainted by the other world.
- Enhanced Mana Sensory: Lemiel possesses the ability to sense mana from his surroundings. He can sense mana from miles away.
- Expert Craftsman: Lemiel is an experienced magic tool craftsman, having created a multitude of tools with various effects.
- Mana Zone: Lemiel can control all the mana in an area around him to increase his spells' power and range.
- Grimoire: Lemiel possesses a four-leaf clover grimoire that contains various light-based spells.
- "I'm positive that this will become a world where our peoples can live side by side, as friends!! We'll be able to understand each other!" 「僕達と君達が必ず共に仲良く生きられる世界がきっと来るよ...! 僕達はわかり合える...! "Bokutachi to kimitachi ga kanarazu tomoni Nakayoku iki rareru sekai ga kitto kuru yo...! Bokutachi wa wakari aeru...!"」
- Lumière is French for "light."
- Lemiel's grimoire design is the background for Volume 21's cover.
- Ironically, the magic tool that Lemiel wanted to use to distribute magic equally was used to steal the elves' magic and to boost the royals' magic.