You could always try one of the 7 daily CONUS flights NW has to NRT each day (8 on Saturdays) and from NRT, grab a 19,000 mile intra-Japan award to either KIX or ITM. Having done NRT-ITM, it's not the most fun you'll have, and make sure you've got plenty of time (at least 2 hours, ideally 3), but if you've gotta go...