99 man Jeonsaengi Nal Dowajwo

As an F-Rank hunter, Kang Hyeonjun struggles to make a living in a world where dungeons exist and monsters are real. But after repeatedly failing to pull his weight in raids and being chewed out by fellow party members, his self-esteem hits rock bottom. To make matters worse, his girlfriend, who has climbed the ranks during their time together, dumps him on their one-year anniversary. When Hyeonjun returns home that night in a drunken haze, he finds himself walking into a dreamscape instead of his humble studio. There, a man claiming to be one of his past lives offers to make him stronger. But as the saying goes, if there's no pain, there's no gain. Will Hyeonjun be able to endure multiple trials and finally obtain the strength he so desperately desires?

(Source: Tappytoon)