Leviathan

Leviathan is portrayed as a mentally immature and selfish demon whose emotions run hot and direct.

She deeply adores Lucifer, whom she calls “Big Sister,” and will throw herself into any danger for her sake.

Her defining trait is envy, and that emotion strongly shapes both her actions and relationships.

In the anime version, her attachment to Lucifer makes her openly resentful of Maria Totsuka, whom Lucifer has taken an interest in.

Leviathan’s upper body is dressed in fairly ordinary clothing, creating a sharp contrast with her lower half.

Below the waist, she wears only a single thick belt like a miniskirt.

When she fights at full power, she appears in armor resembling a bikini armor style.

She does not wear women’s underwear and instead covers her genitals with a single adhesive bandage.

Leviathan has a childish, headstrong, and willful personality.

She tends to act on impulse, especially when jealousy or devotion to Lucifer is involved.

Her affection for Lucifer is intense and obsessive.

She even has a peculiar fetish involving smelling Lucifer’s discarded underwear and becoming aroused while licking the crotch area.

Leviathan specializes in water-based magic.

Reflecting that affinity, many of the monsters under her command resemble aquatic creatures.

Driven by jealousy, Leviathan attempts to kill Maria Totsuka.

She captures and humiliates her, but is ultimately defeated when Maria confronts her with sincere, straightforward feelings.

Lucifer witnesses everything and declares Leviathan’s defeat herself.

Afterward, by spending time together, Leviathan and Maria gradually grow closer.

As their relationship softens, Maria begins calling her “Levy-chan.”

Following the exile of Belial and Astaroth to the surface world, Leviathan remained with Lucifer as one of the rulers of the Seven Mortal Sins.