The Society of the Kuo-Tan was a vigilante organization. They investigated corruption, evil, and vice in the court or abroad and when they discovered any they took lethal countermeasures.
The Society of the Kuo-Tan split from the Tsui Tong when it started to become corrupt. The original founders of the Tsui created the Kuo-Tan to stop their now-evil first creation. In time, they gained the tacit support of the Emperors. In 1357 DR, one of their most powerful members was the maternal grandfather of the current Emperor Kai Chin.