iPad won't recognize JIS bluetooth keyboard

Wish to use a Japan-made bluetooth JIS keyboard with the iPad to match what I have in the office on a Mac.

On a JIS keyboard double-quote is shift-2, @ is next to P, and colon is next to semicolon.

I added software keyboards Japanese-Romaji, Japanese-Kana, and English (Japan). In the Hardware Keyboard setting, the only Japanese keyboard is 'Kana' and it's available only for Japanese-Romaji and Japanese-Kana. Anyway, both of them give a @ for shift-2 instead of a double-quotation.

A forum post from 2010 said that he solved this issue by putting his iPad language to Japanese. I tried forgetting and adding the keyboard with both language and location settings set to Japan but same issue.

I know Apple has a JIS-laybout bluetooth keyboard. Is that the only Japanese keyboard the iPad supports?

Tried with both an iOS 11.2 iPad Pro and an old iPad mini on iOS 10.