[prewett]

Check the tourist visa requirements. China has (or at least had) a 60 day or 90 day multi-entry tourist visa with no maximum number of days. So you just take a trip to Japan ever couple of months and come back. Even if it had a 180 day per year limit (like the US and Europe, I believe), it would be a way to be there, talk to some expats and see what things are like.

Another option is language study through a University, which if you think you will be in Korea for a few years, I would recommend. I tried working FT in China and studying language in my spare time, and in retrospect I would have been better off taking a year (or better, two) to study language, as I never progressed beyond survival+, and that's about the point where the built-in need to learn peters out. This would work well with remote work, especially if you take a light class schedule.

I think that frequently the non-work visas only require that you do not work at a local company paying you in local currency. If you work remotely for a foreign company, being paid in foreign currency to a foreign bank account, I believe that is not a problem. (How would that be functionally different from having your rich parents pay your living expenses? Or living of the dividends of your trust fund?) As far as I can tell when I researched it, even the US is okay with that (and have known several foreign students in the US doing that), but I would advise doing your own research.