Hoegwihan Cheonjae Hunter-ui Seulgiroun Cheongsosaenghwal

World’s first SSS-ranked genius hunter, Junu Kim. He regresses ten years into the past after being ambushed by unknowns one day. With all his hunter skills now locked, he must fulfill his career as a dungeon cleaner to unlock them. But this cleaner… is extraordinary! The once renowned hunter, Junu Kim, takes over the cleaning duty with vigorous determination. Source: Webtoon