May I know on which OS you are working with Adobe Reader?
You can fill a form in Japanese by selecting the language from the Keyboard options.
Thank you for your answer.
I use iOS9.1 and Ver15.1.1 Acrobat Reader for mobie.
Japanese keyboard is available, but I can not input to the confirmation.
May I know which Japanese Keyboard you have selected on your iOS 9.1?
Japanese - Kana or Romaji?
Try to add Japanese Kana keyboard on your device. Then go to the PDF form Acrobat Reader.
Tap & hold the Globe icon and select Japanese - Kana as the language and try to fill the form.
This should save the content in Japanese language.
Let me know if this works.
I use both Japanese - Kana and Romaji.
Both can not be Japanese input.
I can input Japanese in Acrobat Reader DC for Win
At the time of the following settings, it is so that it can not be Japanese input.
’Text Field Properties>Options>Comb of 99 characters’ is checked.