Ultimate God of War

The otaku traveled to the future world and became a little kid. He teases beauties when he has nothing to do, and is teased by beauties when he has trouble. Occasionally, he also practices his favorite kung fu. After the discovery of martial arts, countless years of accumulation led to the fundamental evolution of human life. Those who practice martial arts can destroy mountains, burn rivers and boil seas, and shatter stars. For the protagonist who has lived through one life, he just wants to stop regretting in the new world.