Five years ago, an unprecedented catastrophe occurred in the underground city. The GBL religion launched a war against the underground city, resulting in the death of many innocent people. There was a missionary in the GBL religion. His marksmanship was astonishing and unmatched. He defeated masters from all walks of life. Later, the GBL was defeated. The missionary fell off the cliff and disappeared. Infected by the ruins girl, they became a pair of lovers. A few years later, the missionary gave up evil and turned to good. In order to make up for his mistake of killing the Celestial General, he changed his name to Gus and sneaked into the underground city to secretly help the Principality of Belmare. Later, he also helped his teammates defeat the Ghost Corps and saved the underground city. In the end, the missionary's identity was revealed... Kill or keep? Everything is an unknown mystery