Chang'er appeared due to this mistake. Just when Ziling noticed Sun Wukong in the Pangu Realm, another person behind the scenes also noticed the Pangu Realm and sent one of his underlings, a young man with a sinister air. It was this young man's appearance that polluted the Heavenly Dao of the Pangu Realm, and ultimately, the heavenly dao's projection fell upon Chang'er, turning Chang'er into the embodiment of the heavenly dao. At that time, the person behind the scenes did not give the young man with the sinister air any specific task. Chang'er, who had become the embodiment of the heavenly dao, killed Sun Wukong purely as a manifestation of the heavenly dao's own will.