Xuan Shu was searching for a specific Earth Immortal named Ji Fan.
Ji Fan had achieved Enlightenment several hundred years ago and ordinarily cultivated at Qilian Mountain's Heavenly Dog Cliff, choosing to undergo Soldier Disintegration before the cataclysm.
Since he cultivated a sidetrack method, he feared that reincarnation might cause him to lose his true nature without someone to guide him; fearing a complete plunge into the cycle of rebirth, he secluded himself in Qilian Mountain for one hundred thirty-eight years, torturously refining his Primordial Spirit until he advanced from a Ghost Immortal to an Earth Immortal.
In former years, he had studied Taoism from an ancestor of the Kunlun Sect and became his disciple. Although he never joined the ranks of the Kunlun Sect, a bond of master and disciple was formed, and he refined the Five Thunder Heavenly Heart True Method.
