The Demon Sisters are a nefarious duo of, you guessed it, demon sisters, named Scanty and Kneesocks. These femme fatales are lieutenants of Hell's Secret Police, and they take orders directly from Lord Angron himself, who is Lord of the Police. Scanty is the elder and leader of the sisters, and Kneesocks is the younger, and smarter of the two. Scanty and Kneesocks ruthlessly hunt down souls or demons that disobey the laws of Hell. Once said individuals are arrested, they are never heard from again. They even have the power to summon their own demons, giant or small. The Sisters are noted for attempting to apprehend Blue team after they were thought to be associating with "false demons" and to have started a riot. The sisters currently continue to work in Hell, where they arrest/kidnap POI's in that realm.
Not much is known about the history of the Sisters. What is known is that they were once angels in Aetherius, but they sided with Satan at some point and were kicked out of Paradise. They were corrupted and recruited in Infernus, where Lord Angron, Lord of Hell's Police, recruited them to be his lieutenants, due to their intelligence, proficiency with weapons, and their loyalty to the infernal powers. They were given command of Hell's Secret Police, the primary branch of law enforcement in the realm. Their special division of the SP is known as the "Cleansing Fire".
It was this division that, when Panty and Stocking were identified as a threat to the peace, proceeded to apprehend the unconverted angels. Originally, it was planned that the Angel sisters would be assassinated by the Demon Sisters' personal servant, a Prinny known as Mr. Nailbrain . However, Nailbrain screwed it up, and Scanty and Kneesocks were forced to engage. The mission changed slightly when Blue team was found to be involved with the criminal angels. The Sisters summoned a demon called Bloody Hound to destroy them. Still, the Sisters were unable to subdue Blue team and the angels. The Sisters, enraged, retreated to rethink their strategies. They next appeared when Blue team entered Lucifer's throne room and requested to be taken back to Earth. They appeared out of fire and commanded Blue team to step away from the Devil. After Blue team and the angels were cheated by Lucifer, the Sisters simply laughed and giggled as Blue team was humiliated and were forced to pay a high price for their release; the release of another force of evil. Since Blue team's departure from Hell, the Sisters have so far not been seen again.