Upvote:2
1) Transit Tourists Travelling to a Third Country
- You transit through Korea on your way to the United States (excluding Guam and Saipan), Japan, Canada, Australia, and New Zealand and hold a valid visa (including re-entry permit, but excluding e-visa or Japanese Group visa) issued by the aforementioned countries.
This is your case both ways, it seems, as long as the visa that you have for Japan is not an e-visa.