It's Me, the Fake Hero, Who Saves the World.

The protagonist, Ren, is a modern man who accidentally traveled to a different world. He discovers that he is the descendant of the strongest brave man in the world. He possesses superhuman strength and talent. However, he cannot use his power at will due to his soul travel. Because their ancestors were the strongest brave men and led their knights to defeat and seal the eight most powerful demon kings hundreds of years ago, the demon kings are looking for opportunities to take revenge on the descendants of the brave men who sealed them and rule the entire world. Although the protagonist cannot use his abilities at will, his IQ has not been affected by soul travel, and will instead be higher than before. The protagonist decides to rely on his own wisdom and unique magic props to create his own brave character. At the same time, because the devil will always be his enemy, he has to embark on the road to save the world. On the way to explore the world and contact the descendants of the companions who sealed the Demon King with their ancestors, they encountered many interesting or thrilling experiences. Some of the descendants of the warriors are tired of fighting, some are eager to restore the glory of their ancestors, some are just to comply with the last wishes of their ancestors, some are just to surpass their ancestors, and some have even surrendered to the Demon King and become the minions of the Demon Clan. The protagonist has to find new power while contacting the forces of all parties.