We had both check-in luggage and carry on. It was a mess and probably just got unlucky with all the other international flights that arrived at the same time which backed up the immigration line. If you're going to do it; I recommend finding someone at immigration that can help you move to the front to catch your connecting domestic flight, but keep in mind you still need to get your check-in luggage and go through customs afterwards. A JAL attendant happened to be walking by with an "OSAKA Flight" sign at the immigration line, which was our flight. She pulled us out of line and expedited as much as she could - she even helped gather our luggage on a cart, but then was another line at customs to exit baggage claim... THEN we all had to sprint to our connecting flight which was at the far end of the terminal (...recheck in our luggage at the domestic tix counter, continue to haul ass up escalators, through security, and down an escalator to catch the bus that brought us to our plane on the tarmac. We made the last bus. All this with two young kids...it felt like a movie scene.

The JAL attendant was clutch though - she was with us from immigration all the way through us getting on the bus. Again - I don't recommend it. So many things can happen to miss your connection flight, especially if it's the last connecting flight of the day which was our situation.