Representing the demon Belphegor and the corresponding the sin of Sloth. Belphegor's appearance is a girl with long dark hair in a pony tail. She is hard working and sensible, to make her target fall all the harder. She is the middle child of the 'Stakes of Purgatory'.

Spoiler

She is the fantasy version of one of the servants that used to bully Sayo Yasuda as a child.

(Source: Wikipedia)