Mount Tai City, provincial capital of Insignia Province.

Traffic was heavy, and the streets were filled with pedestrians. Professor Yu sat within a nondescript, low-profile villa, staring into his computer screen. Three men dressed in white lab coats stood patiently in front of his table. The title of the document displayed on the screen read “The Evolution of Yin Spirits and Their Adaptation to the Environment”.

“Let’s halt the work on this for now.” Professor Yu massaged his temples with one hand and waved his other hand. His personal assistant immediately brought over a cup of tea. He sighed, and then furrowed his brows at the LED screen, “It doesn’t work.”

The three men in white lab coats chuckled bitterly, and the middle one sighed, “The information is really lacking. You’ve been whole-heartedly devoting your attention to this research topic ever since your return from the City of Salvation. We’ve searched the records throughout the country, and we’ve located no more than a few dozen cases where mutation was but a possibility. But if we compare these numbers to the total number of Yin spirits around, the results we have are completely insignificant.”

Professor Yu shut his eyes and grew taciturn.

He recalled the day when the young man swore to him that the mutations of Yin spirits were by no means isolated examples, and they had in fact been occurring since time immemorial. Unfortunately, his busy schedule meant that he had to return to Mount...