Levi is an Ancient Belkan knight and one of the three beings known as the Materials, alongside the king Dearche and their friend Stern. Their soul was originally sealed within the Tome of the Night Sky and later released, with a physical body formed from the data of Fate T. Harlaown by the antagonist Iris. Levi first appears in the film Magical Girl Lyrical Nanoha Reflection and continues to play a supporting role in the sequel Detonation. Their exact age is unknown, and their gender is not clearly defined within the narrative.

In terms of personality, Levi is fierce and combative, displaying a strong sense of loyalty to Dearche and Stern. They are driven by a desire to protect their companions and to fulfill their role as a Material. Their motivations stem from their origins as a fragment of the Tome of the Night Sky, and they act as an obstacle to the main characters during the conflict. Over the course of Detonation, Levi engages in battles against Nanoha Takamachi and her allies, showcasing a straightforward and aggressive fighting style.

Levi’s key relationships are with Dearche and Stern, with whom they share a deep bond as fellow Materials. They also have a connection to Fate Testarossa, as their body was constructed from Fate’s data, though this does not translate into a personal relationship. In the story, Levi serves as an antagonist aligned with Iris’s plans, but their loyalty is ultimately to their own kind rather than to a particular cause.

Notable abilities include mastery of lightning-based magic, which is reflected in their title Levi the Slasher and the name Levi being a pun on the archaic word levin meaning lightning. They wield a device called Vulnificus, which allows them to perform rapid slashing attacks and high-speed combat. Their magical talents are derived from Fate’s data, giving them similar traits in terms of speed and electrical attacks. In battle, Levi is a dangerous melee fighter who relies on agility and powerful strikes.