Lucifer is the central protagonist of the anime Seven Mortal Sins, also known as Sin: Nanatsu no Taizai. Originally a high-ranking archangel and the former leader of the Seven Heavenly Virtues, she was cast out of Heaven for rebelling against God's will, an act driven by her overwhelming pride. While falling, she briefly crashes through a high school church on Earth, where she encounters a young girl named Maria Totsuka. Lucifer infuses Maria with some of her angelic blood before continuing her descent into Hell. Upon arriving in the depths of Hell, she is met by Leviathan, the minor Demon Lord of Envy, who becomes her enthusiastic follower.

Lucifer is soon challenged by the ruling Seven Sins, a group of powerful Demon Lords led by Belial. The Seven Sins combine their strength to overpower Lucifer, sealing her angelic powers by placing a cursed Garb of Punishment on her body. This cursed tattoo-like chain inflicts constant pain and bloodletting, transforming her into a Demon Lord. Swearing vengeance, Lucifer returns to Earth with Leviathan, where she forces Maria to become her immortal slave. With these two companions, she sets out to defeat each of the Seven Sins individually, intending to break the Garb's hold and reclaim her freedom.

Lucifer's personality is defined by her immense pride and arrogance, often looking down on others and acting with a commanding, dominant demeanor. She exudes a sense of authority and confidence, sometimes coming across as cunning and ruthless. Beneath this exterior, however, she harbors a more naive and straightforward side, easily charmed by sincere compliments. Her primary motivation is revenge against those who humiliated and cursed her, as well as a fierce desire for true freedom from both Heaven's rule and the Garb of Punishment. Throughout the series, she demonstrates a strong will and strategic mind, but her pride can lead her to make reckless decisions.

Her role in the story is that of the protagonist seeking to overthrow the current rulers of Hell and eventually confront the archangel Michael. Her journey involves direct confrontations with each of the Seven Sins, often challenging them in contests reflective of their respective vices, such as a pole dancing competition against Asmodeus or a food-eating contest against Beelzebub. Her relationships are central to the plot: with Leviathan, she has a dynamic of reluctant leader and devoted follower; with Maria, she holds a master‑servant bond that develops into something more complex; and with the Seven Sins, she is both enemy and eventual redeemer, as some later side with her against Belial.

In terms of development, Lucifer begins as a proud fallen angel stripped of her divine power. As she defeats each Sin, she grows stronger and more determined, though she also faces moments of vulnerability and empathy. Her character evolves from a vengeful outcast to a leader who gathers allies, ultimately facing Belial in a final confrontation that tests her pride and resolve.

Lucifer possesses formidable abilities. As a former archangel, she originally wielded holy power, but after being cursed, she becomes a Demon Lord of Pride. Her physical strength is immense, and she wields a large scythe as her primary weapon, capable of delivering lethal strikes. She has large bat‑like wings that allow flight, and her appearance is tall and voluptuous, with long white hair and deep red eyes, typically dressed in tight black leather. The Garb of Punishment itself is a source of torment but also binds the power of the Seven Sins; by defeating them, Lucifer gradually weakens the curse. She is also skilled in psychological manipulation and strategic planning, often outwitting her opponents rather than relying solely on brute force. Her pride itself can be seen as both a weakness and a source of strength, driving her to overcome seemingly insurmountable odds.