Overview
They were also known as the Owner of Salt Mountain, and the Axle Imperial Venerable.
They were the former Castle Wall Heavenly Lord of the Radiance Ten Heavenly Lords, and the first of the Radiance Heavenly Lords to defect. They took their mask along with them, preventing a successor arising for their position.
After their death to the Gatekeeper, They repeated their life as Cheongmun Ryeong until he were absorbed by a salt pillar. They had their final death as "Salt Sea Master Cheongmun Ryeong" inside the dream realm.
Relationships
They were the master of Gwak Am and Seo Eun-hyun. His remnant will appeared in the dream realm in the form of Cheongmun Ryeong, which taught Seo Eun-hyun the essence of Immortal arts.
Legacy
They are the creator of the Penglai Kingdom (Along with Hyeon Rang and a few Heavenly Kings from Obsidian's generation) and filled it with stolen light, allowing people to talk without having to be wary of [Light]. However, over time the light from the outside mixed into the light of the Kingdom, meaning that there is only a small room left with untainted light. It is a kingdom where [Snakes] cannot enter.
According to Hyeon Mu, He could have became the Heavenly Venerable of Purity if it wasn't for the Enders, and became a True Emperor candidate 8.4 trillion years ago.