The Four Great Demon Kings

Answer 1

In A Record of a Mortal's Journey to Immortality, the four demon kings of Earth Abyss were Mu Qing, Liu Zu, Di Xue, and Blue Onibaba.

Liu Zu was the strongest of the four. He was from the Mayfly Race and was the one who initiated the entry into the infernal river. He was more familiar with the situation there. After entering the Netherworld River, he was attacked by the Mayfly Tribe and Infernal Lightning Beast. He defeated the puppets possessed by the Mayfly Tribe and obtained a portion of the Netherworld River Divine Milk. He then reached an agreement with Di Xue and the Onibabas to go to the Demon Tomb to search for treasures to monopolize the remaining Netherworld River Divine Milk. In the end, he was trapped by the replica of the Holy Nest released by the Mayfly Tribe guards. He was captured and brought back to his tribe, where he was expected to be executed.

Mu Qing was a demon king who had cultivated to the form of a wood spirit. He had personally captured Han Li, who had impersonated the Sky Roc Sage to participate in the Earth Abyss Trial. After discovering that Han Li possessed Divine Devilbane Lightning, he had taken him to meet the other demon kings and coerced Han Li into helping him. He had even requested that Han Li learn the Lightning Sacrifice Technique, and Han Li had spent more than two years under his guidance. After entering the infernal river, he was also caught in a pincer attack and was predicted to be executed. His realm was at the late-stage Body Integration realm, and his ultimate technique was the Heavenly Flower Chaotic Leaf Formation.

Di Xue was a demon king proficient in puppeteering techniques. He had refined the Purpleblood Puppet and fused his primary soul with it, allowing it to unleash the strength of a Body Integration cultivator. He had asked Han Li to refine puppet armor for him, and he had taught Han Li many secret puppet techniques. After entering the infernal river, he was caught in a pincer attack and was predicted to be executed. His realm was at the late-stage of Body Integration. His ultimate technique was the Dual Fiend Demon Body, and his treasure was the Evil Warding Armor.

Blue Onibaba (Onibaba) had nurtured 8,000 Yin Armor Profound Ghosts. After entering the infernal river, they were captured and brought back to their clan, where they were expected to be executed.

While waiting for the TV series, you can also click on the link below to read the classic original work of "A Record of a Mortal's Journey to Immortality"!