All the young F/O's at AirJapan that are USCitizens have apps with the majors in the US...., not that the job is bad mind you (although it used to be a lot better) but you will simply do better back home, both economically and in job security...., Air Japan has pretty much refused to take a look at pay, period! they are convinced that their pay package is still competitive...., it is a contract job and every 5 years is just a lottery on renewal, most people get renewed but there are some that have been let go..... And the upgrade is really a lottery..! Latelly the failure rate is between 40-50% and if you get bumpt twice, that's it! permanent F/O...
For many people works great but for a young pilot such as yourself my recommendation is to try to make a career back in the US....., if you like Asia, you can always try to get based out here with UAL, FDX, DAL etc that operate bases out here.
Good luck!