(I mean, in the LN the Japanese at this point in the story are already clear Villains, literally(!) sheming to get the korean hunters killed, so they have a even bigger edge over korea (which has one of the weaker hunter forces of the big nations, they are inferior in quality and massiv in quantity to Japan in terms of high ranking hunters))
And well "messed up" more like killed, they cant really change that all japanese hunters die, since thats the reason for a later storyarc.