It\s because every key on your keyboard is one hiragana... It\s like that for me as well, I don't know how to change it.
Take a look here:
Japanese Hiragana Keyboard Layout
(takes a bit to load)
The only think I know of that you could do is somehow mark the keys so you know which one is which hiragana.
Example of a solution:
JAPANESE HIRAGANA TRANSPARENT KEYBOARD STICKER BLUE - eBay (item 260323857655 end time Mar-29-09 03:09:54 PDT)
These are fairly inexpensive, but still...
If anyone knows how to fix it so when you type letters from the latin alfabet they turn into hiragana, I'm sure that's better.