According to the search results provided, there was no mention of what Black Impermanence looked like in his previous life.

The Black and White Impermanences were Xie Bi 'an and Fan Wujiu in his previous life.
The story of the Black and White Impermanence in his previous life was about a pair of good friends, Xie Bian and Fan Wujiu. They lived in Fujian during the Western Jin Dynasty. Xie Bi 'an was a scholar, and Fan Wujiu was a warrior. They were sworn brothers. In a battle, they risked their lives to save the famous general Wen Tianxiang. According to different versions of the explanation, they had a wonderful life in the human world and were ordinary mortals. In order to support their families, they joined the local government office and became two constables to catch criminals. Despite the hardships and dangers of life, they always looked out for each other and worked hard, winning a good reputation in the local area. However, in the end, they became the Black and White Ghosts, responsible for taking away the souls of the dead. This story showed their deep friendship and their spirit of fighting for justice.
The Black and White Impermanences were Xie Bi 'an and Fan Wujiu in his previous life.
The White Impermanence and the Black Impermanence were a pair of gods in the traditional culture of the Han people, and they were also the most famous ghost officers. They were the Soulbringers, responsible for capturing ghosts and helping to reward good and punish evil. The White Impermanence was called Xie Bi 'an. He was tall and thin, and his face was pale. The Black Impermanence was called Fan Wujiu. He had a fierce face, a broad body, and a small black face. They were handcuffed and shackled, and often worked under Hades, Shing Wong, Emperor East Peak, and other underworld gods. Therefore, White Impermanence and Black Impermanence could be called ghosts.
The Black Impermanence and White Impermanence looked like they were ferocious, fat, short, and had a face like charcoal. They wore a black hat and black clothes, and their skin was dark green. White Impermanence often smiled. He was tall and thin, with a pale face and a long tongue. He wore a tall white hat and white clothes.
The Black Impermanence and the White Impermanence had different descriptions in traditional culture. We can see that Black Impermanence's appearance is usually dark and green, wearing black clothes and a black hat. He is short and has a fierce face. White Impermanence was dressed in white. His face was pale, and he was smiling. He wore a tall white hat with the words " Wealth in Life " written on it. However, because the search results did not provide a specific picture of the person, they could not provide an accurate picture description.
White Impermanence's original name was Xie Bi 'an, while Black Impermanence's original name was Fan Wujiu.
In China mythology, the Black Impermanence represented severity and punishment. His name "Wuchang" implied the impermanence of life and death. Everything in the world was constantly changing. In traditional China culture, the image and legend of Black Impermanence embodied morality and values, including the meaning of fairness, benevolence, justice, and blessing. His duty in the netherworld was to seize souls, not only limited to humans, but also all other living beings. The image and legend of Black Impermanence were widely used in literature, opera, folk beliefs, and so on. In short, Black Impermanence symbolized the punishment for evil deeds and the pursuit of justice.
Black Impermanence and White Impermanence were the demon spirit characters in the mobile game Night Walk of God's Capital.