Called JAL Priority Guest Center phone number in Japan (0120-747-707; for passengers requiring special assistance) regarding a flight I have tomorrow from Japan to the US on a 787. Call center spoke only Japanese, but offered to give me the English reservation desk phone number in Tokyo. I declined and successfully made my request to bring my CPAP (ResMed AirSense 10) onboard in my mediocre Japanese; I was put on hold for two minutes and the request was approved. This is the SkySuite 787 with seat power throughout; in-seat power is apparently a requirement for CPAP operation on JAL. I was asked to present the CPAP to the JAL check-in staff before departure.
Was kind of expecting this sort of short notice request to be denied, but JAL was very cool about it. Note that I am flying in J (and have lolCrystal status), so they may have been more accommodating for this reason.
BTW: "CPAP" is pronounced "see-papu" in Japanese. Or at least the JAL staff member understood what I was requesting
More info in somewhat okay English:
http://www.jal.co.jp/en/jalpri/illness/sleep.html