If you are still looking for a Japanese dictionary, please try out BB Jisyo at BB Jisyo - Japanese Dictionary for Blackberry
. This dictionary supports Japanese input (kanji etc).
Also has access to a 160,000 sentence database of English - Japanese examples.
Its tested and works on the 8707h (yes, Japanese input is possible on this device). I would be interested if anyone could give it a try with devices which only support Japanese fonts (not input).