[Sangetsu]

You should hunt on Ebay or Yahoo Japan auctions for Japanese-market Docomo or Softbank phones. My Docomo 904 telephone has a built-in dictionary which converts English to Japanese, and vice-versa. What's more, I can take a picture of a sign or page written in Kanji with the phone's camera, and translator in the telephone can read the characters and convert them to English.

Some Softbank phones are unlockable, and can be used on American 3G or GSM networks. Unfortunately, Docomo phones are not unluckable, but used ones are cheap, and you can still use some of their features (such as the translator/dictionary) overseas.