[throwawaaarrgh]

You don't get a transfer if you've bought two separate flights. You have to pick up your luggage and put it on the next flight.

[seanmcdirmid]

If the airlines have agreements, you can often get your luggage automatically routed to your next flight. I used to do that between Alaska Airlines and Hainan. Not sure if you can get that done in Tokyo, but it wouldn’t surprise me if it were actually possible.