Who is the sick old man?

The sick old man in Covering the Sky refers to Jiuyou Gai. He was ill when he first appeared, making people unable to look straight, but his real strength is very strong. Before that, he had killed the emperor.

"Covering the Sky" Jiuyou Gai Nine thousand years ago, the wizard of the earth in Beidou Zhongzhou, the strongest Terran in the world, was close to enlightenment. Injured by the failure of Tao 8,000 years ago, he was forced to return to the peak when the sky was dark and turbulent, and he died with the Lord of the city of God.