Zhang Xuanji initially sought out Qing Yu, thinking that Qing Yu would engage in alchemy for three months as a trade, and have Qing Yu help him exact revenge.
However, Qing Yu later became interested in Zhang Xuanji's alchemy skills, and through a combination of persuasion and pressure, forced him to stay for another three months after three months, and before he realized it, nearly three years had passed.
By now, Zhang Xuanji had almost become the Imperial Alchemist for Northern Zhou, dedicated to refining elixirs for the Imperial Family, as well as developing new elixirs.
With the Imperial Family providing Zhang Xuanji with herbs, a large workforce at his disposal, and no restrictions on his independent research, coupled with Qing Yu's increasing influence, Zhang Xuanji settled comfortably into his new home in Northern Zhou.
This Mad Demon Pill was precisely developed by Zhang Xuanji at Qing Yu's behest, for today's great battle.
