it's the apple wireless bluetooth keyboard in American English format.
it's the same keyboard I use to input both English and Japanese on my computer, so the hardware's inability to do one or the other shouldn't be the issue, as I understand it. in the firmware, when I press command+space to switch to Japanese, iOS recognizes the command and switches over to "allow" me to start typing in Japanese. Sometimes I'll be able to do so without a hitch for a couple minutes, and other times the app crashes as soon as I type my second character.