The japanese music industry is thriving, in both the japanese and foreign markets. The Korean industry ****ing sucks. So they saw the popularity of Jpop in foreign markets and basically just copied that. But there are issues. First, idol culture in japan is vile, they contractuall stop stars from being seen with loved ones or even having romantix parteners. Korea copied that too. But also they're super racist and, where Japan loves mixed race idols, korea treats them like shit. So, yeah.