Namgungsega Cheonjae Oesonja

The disaster of the destruction of a clan befell Ha-hyeon, who was only ten years old. Having lost both his house and his family, Ha-hyeon barely managed to survive and arrived at Namgung Segae, where he tells his maternal grandfather, "The Sword Lord Namgung Mu-ryong." "I don't want to lose anything precious anymore." Namgung Mu-ryong, who saw Ha-hyeon's will to walk the path of righteousness with an upright heart even in a desperate situation, sends him to the entrance exam. There, Ha-hyeon acquires and utilizes martial arts that he had never learned before just by looking at them, and begins to stand out with amazing achievements. The path of the best in the world, walking as a genius given by heaven, 'Ha-hyeon' and 'Namgung', unfolds!

(Source: KakaoPage, translated)