Not you leaving Big Bang out when they are by far the biggest Kpop act.
Anyway, Kpop is way more popular around the world but despite Kpop being so widely known, South Korea is a relatively small music market. On the other hand, Japan is a HUGE music market (just about tied for #1 with the US) and makes so much more money than the Korean music industry. The scale of revenue between the two isn't even comparable. There's a reason Kpop acts are flooding to promote in Japan.