I noticed that ROKU now has a KPOP (Korean pop music)
channel, but still doesn't have any kind of Japanese or JPOP
channels. I sure wish they would add Japanese channels to the lineup
because i understand a little Japanese, but Korean is just gurgling noise.
It's not readily apparent to most that each channel provider creates and maintains the specific version of their app that runs on the Roku system. The only channels that Roku maintains are their own The Roku Channel, the Roku Media Player, and several Roku information channels. For everything else, Roku just provides the platform on which they run.
For additional services you'd like to have available via Roku, contact them and let them know.