What is the meaning of Tianshi Zhongkui! Why is he called Zhong Kui, the Heavenly Master?

Zhong Kui was alive when he inherited the ancestral business, is to catch ghosts (similar to the ancient Taoist profession), because of a small thin name, known as "ghost hunter Tianshi". Legend has it that he became an immortal after his death and continued to be honored by the Heavenly Court as a "Heavenly Master", responsible for clearing up wrongful convictions and restoring innocence. Folk also Zhong Kui and Qin Qiong, etc. as a door god, blessing the family peace.