Astaroth is a significant character from the anime series, known as the Demon Lord of Melancholy. As one of the Seven Deadly Sins, her nature is intrinsically tied to her title, manifesting in a personality defined by a deep-seated lack of self-confidence and a persistent feeling of inferiority. She often perceives herself as weaker and less capable than others, both in terms of appearance and ability, a belief that isolates her and makes interacting with strangers, particularly large crowds, a source of great distress. This negative self-perception frequently leads to bouts of depression, and she requires considerable encouragement from those close to her to overcome her anxieties.

Despite her melancholy disposition, Astaroth possesses a genuine and passionate love for music. This love is so profound that it drives her to pursue a career as an online singer and idol, a seemingly contradictory goal for someone with such severe stage fright. To reconcile her ambition with her fears, she primarily shares her music through homemade videos uploaded to the internet, finding a safe space to perform away from a live audience. Her artistic expression is her primary outlet and the central pursuit that gives her direction.

Astaroth's most significant relationship is with her friend, Belphagor. Belphagor serves as a crucial pillar of support, often providing the necessary encouragement to lift Astaroth from her depressive states and bolster her fragile confidence. In the story, Astaroth demonstrates a strong sense of loyalty. Despite having met and confronted the protagonist Lucifer, she ultimately chooses to side with Belial in opposition to her, showing that her allegiances are guided by more than initial encounters.

Regarding her role and power within the group of Sins, Astaroth is explicitly noted to be the weakest among them, a fact she herself admits. Consequently, her individual combat abilities are largely unknown, as she tends to avoid direct conflict. Her development does not center on gaining physical strength, but rather on navigating her personal insecurities and stage fright while pursuing her passion for music. Physically, Astaroth has a distinctive appearance characterized by pink hair and pink eyes. She is often depicted carrying an electric guitar, which serves as both her instrument of choice and her signature piece of equipment.