Academy’s Genius Swordsman

Alternative:

Academy’s Genius Swordmaster / 아카데미의 천재칼잡이

Ronan lived a wasteful life filled with regrets. A second chance befalls him at the end of his futile life. He went back to the time when he was a ten-year-old child! For the people who sacrificed themselves for him, he becomes determined to live a new life.