You Are About to Die, but You Can Defeat the Demon King with One Punch?

Lu Yun traveled to a world where spiritual energy was revived and ferocious beasts were rampant. Martial arts were prevalent here. He thought he would become a warrior with thousands of auras, but found that he was seriously injured, and there was a curse in his body. He only had three days left to live... Until the system wakes up... [Detect the host and kill a one-star monster, and the health value will be increased by 1 hour...] Modern medicine can't save me, so why can't I kill a one-star monster? Watching Lu Yun, who was vomiting blood and looking pale, kept killing monsters, countless people burst into tears, arousing a training frenzy. Classmate: Brother Yun is almost dead, but he is still persisting, but I am wasting my time. I really... From today on, I will follow Brother Yun's example. Teacher: Having a student like Lu Yun is the greatest honor in my career... School Belle: Be my boyfriend, leave some time for me, and have a good rest. After a while, when Lu Yun punched the demon king, everyone was numb. Aren't you going to die? What does it mean to kill the demon king with one punch?