Myst, Might, Mayhem

All Jeong wants is a second chance — for revenge! His grandfather’s gruesome death has transformed him into the bloodthirsty and ruthless Scythe Demon. He will stop at nothing until he has killed the man responsible. Yet rage and determination alone are not enough. He must train in martial arts if he ever wants to stand a chance against such a formidable foe. Will he succeed in his revenge on the murderer of his grandfather?
(Source: LINE Webtoon)