Belphegor, as depicted in the anime Seven Mortal Sins, is the demon lord who presides over the deadly sin of Sloth. She is one of the seven primary rulers of Hell, each embodying a fundamental vice. Her physical appearance is distinctive and aligns with her nature; she is presented as a young woman with short, white hair and animal-like ears, often seen wearing casual, comfortable clothing that reflects her preference for staying indoors and avoiding exertion.

The core of Belphegor’s personality is a profound and encompassing laziness. She is a quintessential recluse, almost always found holed up in her own room, where she spends her time idly. Her speech is frequently punctuated with complaints about things being troublesome or bothersome, and she actively seeks to avoid any form of work, duty, or confrontation. This indolence is not merely a preference but appears to be the very essence of her being as the master of Sloth.

However, this characterization comes with a notable and ironic contradiction. Despite her overarching laziness, Belphegor is capable of immense diligence and effort, but only when it pertains to her personal hobbies and interests. Specifically, she is an avid enthusiast of anime and video games, two mediums that exist within the human world she is meant to oversee. In these areas, she sheds her lethargic persona and becomes a surprisingly active and passionate participant, willing to go to great lengths to enjoy her chosen entertainment. This reveals that her sloth is not a total lack of energy but a profound apathy towards anything she does not personally find engaging or pleasurable.

Her role within the story’s narrative is shaped by this unique combination of laziness and selective passion. Rather than directly confronting her enemies or actively scheming to spread sin in the physical world, Belphegor’s methods are more modern and passive. She has been shown to use the internet as her primary tool, building a global network of followers and believers from the comfort of her own room. This approach allows her to fulfill her duties as a demon lord and spread the influence of sloth without ever having to exert herself in a traditional manner.

Regarding her abilities and standing among the other demon lords, Belphegor possesses a hidden potential. While she rarely demonstrates her true power due to her aversion to effort, it is suggested that when she is pushed to her limits or decides to become serious, she is arguably the strongest among all the demon lords. This latent power is a stark contrast to her usual passive demeanor, making her a wildcard whose full capabilities are seldom seen. This potential, combined with her global reach through the internet, establishes her as a significant, if often understated, force within the hierarchy of Hell. Her key relationships with the other sins are largely defined by her avoidance of them, as she prefers isolation to social interaction, with her primary connection to the world being through her online activities and hobbies.