I think it is more like 15 or 16 hours, no?? since Central time is 13 or 14 hours behind Japan right now (I got all confused since Japan doesn't have Daylights Savings) and California is 2 hours behind Central time.
So, I think just like check on a website like Orbitz and it'll say there departure time and arrival time in Japan just so you can get an idea of the time difference.
Mauricio