While outland is faster, usually, it all depends on the person. The benefit of inland is that you can stay with your spouse without having to deal with things such as visa extensions, even for visa free countries. The drawback is that you cannot appeal the case if they deny you sponsorship. They are both advantages and drawbacks to both approaches that's for sure.
For Japan, I think outland would probably be the better choice, it still takes a while for the process to complete, seems to be kind of in the middle of both extremes (Super fast processing in 5 months or processing that takes over 40 months)
For Japan, I think outland would probably be the better choice, it still takes a while for the process to complete, seems to be kind of in the middle of both extremes (Super fast processing in 5 months or processing that takes over 40 months)