The Knight Who Keeps Coming Back

All the strong men of mankind gathered together, an elite force of more than 10,000 people, and an extremely glorious scene, just to eliminate the prophesied devil. Unexpectedly, mankind was completely defeated. Heroes among mankind began to attack each other. The legendary sword master suddenly rebelled. An ordinary knight witnessed all this with his own eyes. After giving his last effort, he died... Died at the hands of his own people... After his death, an hourglass began to turn upside down, and the knight returned to the day before the expedition with his memory...