gtseraf is basically correct - if maybe a little shy.
Happy to be corrected - but there is NO WAY a paper transfer from FAA to JCAB can happen for a gaijin.
You hear enough horror stories from the young'uns who have headed to the states then come back with the FAA licence; it may work out a little cheaper overall but tons and tons of bull****.
One thing you have to understand - your "experience" may get you a position but once you lob into Japan you have NO EXPERIENCE and will be treated as such...because the only TRUE experience in the known universe is in JAPAN in a JAPANESE opertion.
Anything else is simply inferior, foreign delusion.
Get a position - get the licence as a consequence.
Cheers.