Get used to it guys, NOTHING ever happens quickly in Japan. There are NO shortcuts, and there is a set protocol for everything - that protocol may have been established 10, 20, or 30+ years ago, but it must still be followed to the T today. (In other words, everything is a "ceremony").
There will be certain committees that your applications will need to be approved by - and not just within the airline.
Stereolab asks, "Are your certificates transfered after you complete your checkride?"
You will be required to:-
(i) pass the exams for the issue of a JCAB licence - they do NOT validate licences from other countries;
(ii) do the full ground school, and pass the exams for the aircraft type for which you are being recruited - in this case the Dash 8;
(iii) do the full simulator training, followed by a JCAB check ride;
(iv) complete line training, followed by at least 1 (and perhaps 2) JCAB check rides.
Expect to be "monitored" by the Company and JCAB for the next 12 months-2 years.
No other type rating you hold are transferred - quite simply put, they don't recognise anything done outside Japan, (including previous flying experience) by foreigners flying non JA registered aircraft.
(Ever wondered why you NEVER see experienced Japanese pilots flying for non-Japanese carriers?)
If you are coming to Japan, it's a long, hard slug. Forget about your previous experience, and accept that you will be treated as an ab initio for about 3 years.
Even after that period of time, do not expect to be treated too much differently - a Japanese pilot with less than (for example) 1/2 of your experience will ALWAYS (in their minds) be a more reliable source of info than you.
Japan has a culture of a "closed society" (excluding non-Japanese), and this extends into aviation, and onto the aircraft as well, which makes for "interesting" CRM at times!