Am i the only one who feels like that this is going boring??

Yeah I felt that too. I think part of this issue is the incoherency of the plot. He fought the demon king's clone and won. I think it would be safe to assume that the clone was way stronger than any of the monster he's currently facing or faced in the game. Yet he seems to be struggling. I maybe wrong but I don't believe when he was sent back to earth he had any penalties in regards to his combat power so then it becomes why is he struggling so much or not dominating them? I'm all for plots where the MC isn't stupidly op but if your gonna do that at least make the plot line up with that.