I Will Survive Forever with One Sword

Gu Changge has lived for one hundred and twenty years and still looks like he is twenty years old. An iron sword and a green shirt, walking from south to north. Demons eat humans, and he kills demons. When people do evil, they kill. The more monsters he kills, the longer he lives. A hundred years ago, he taught a child three moves of sword. A hundred years later the child's grandson asked him: "Who are you?" He said: "A guest in this world in a hurry." After saying that, he put his sword on his back and hit the road again.