Mystery: The Gray Earth Man Lit the Remaining Fire

A fanfiction of Mystery x Ember of the Long Night. I, Shang Jianyao, came into this world with only one goal: to save all of humanity! But who would have thought that upon opening my eyes I would find myself drinking an apprentice's potion and encountering the Night Watchman collecting gas meter readings... This is the story of Yao-ge saving all of humanity and his teammates with the help of the "New World"! PS: In the Mystery world, the New World has become Source Matter.