I concur with the previous poster. I found it is easy when you take a very short nap on the flight going westbound to Japan, then go to sleep at the normal bedtime on Japan time. Then you will find you rise at 4-5am in the morning (I found this out on the first time to Japan), it feels weird but it works out alright after doing it for several days to acclaimize yourself to the Japan time zone.

Sanosuke!