A couple of thoughts for the OP:
1) If you are willing to buy a one way LAX-YVR, the roundtrip YVR-NRT is about $1200 in H. It takes up more flying time on the outbound (LAX-YVR-SFO/SEA-NRT), but it's just an FYI.
2) You might consider using you miles for a business class award ticket.