Ning Zhenzi was actually transformed from the Primordial Worm; it lacked the courage to battle Chen Shi and fled in panic the moment it encountered him.
It had been psychologically scarred by Chen Shi.
Years ago, Chen Shi twice refined its physical body in the Xunjiang Star Domain, leaving it helpless, making him its natural enemy. This time, in search of Cangyuan, had it fled slower, Chen Shi would have refined more of its body.
But on its escape route, it found Chen Shi wounded by Subtle Taoist Monarch and Emperor Wan Shou, and formulated a plan.
Rather than being suppressed by Chen Shi, why not take this opportunity to eliminate him forever?
Hence, it gathered physical bodies from the nearby star domain, transformed into Ning Zhenzi, and lay in wait for Chen Shi and his companions.
Ning Zhenzi was indeed a real person, an Immortal from Sanfu Island, but the true Ning Zhenzi had already died.
