Thirty years ago, the "resonance phenomenon" suddenly appeared on a global scale - some humans can create spiritual links with "old things" that have existed for more than 50 years, awakening the "martial arts imprint" deposited in the old things, thus gaining power beyond ordinary people. These people are called "resonators." The phenomenon of resonance only exists in cities (where old objects are densely packed), and there are almost no resonances in the countryside; and the more old objects carry a "strong will" (such as a warrior's sword, a craftsman's carving knife, a scholar's manuscript), the stronger the martial arts mark that can be awakened.
