Why do you need dedicated server mainly located in Japan or Korea? I strongly believe that US-based web hosting provider would be also a good option for you. I think that if you look at several dedicated server offers, you will find the best place to deal with. Have a look at
serverpoint.com,
hostime.com and
globaltap.com. All these companies have nice reputation for providing friendly support and uninterrupted hosting services, so you can choose the best one for you.