During my recent trip to Japan I decided to rent a pocket WiFi so I'd have data on the go, and I have to say it was one of the best decisions I made on this trip. I selected the LTE model, and the internet was blazing fast. The whole set-up is pretty convenient, too - I reserved and paid for the device rental online, picked it up at the airport terminal (there is also an option to have it delivered to the hotel), and then at the end of the rental period I just slipped everything into the prepaid mailer envelope and slid it down the post office box at the airport. Easy peasy. If you're like me and you get data withdrawal symptoms I highly recommend you get one if you're going to Japan. There are a number of companies to choose from; I ended up with Japan Wireless, although my first choice was Global Advanced because they had more competitive prices but they were all out.
Anyway, on to my favorite travel apps.
It's a very convenient (and effective) way of keeping track of my travel itineraries. I just forward everything to the TripIt e-mail address, and it sorts out all the information and presents it in a more organized manner. You can also subscribe to the TripIt calendar so you can see your trip plans on your Calendar app (both iPhone and Mac).
2. Dr. Moku's Katakana
The Japanese writing system has three sets of scripts: Kanji, the adopted Chinese characters; hiragana, used for native words; and katakana, used for foreign words. It can get insanely complicated, and it probably doesn't make sense to learn all three for a week's stay. It is, however, quite helpful to learn katakana, because more often than not, it is used to spell English words. For instance, recognizing the characters チーズ can save you from having floating bits of grated cheese on your curry (the Japanese have an inexplicable habit of sprinkling cheese on just about anything).
It can be scary at first, but it's possible to teach yourself katakana in one weekend. Dr. Moku's Katakana takes it a step further and associates each character with a picture to serve as a mnemonic device of sorts. Not all of them make sense to me, but it's better than writing the characters over and over until you have them memorized.
3. Japanese!! by squarepoet
It's not as fun (and colourful) as Dr. Moku's, and the two exclamation points are driving me crazy, but this app is free and it also contains hiragana as well as some common kanji (and even some "fun" ones such as "communal bath house"). Did I mention it's free?
4. Navitime for Japan Travel
Hyperdia and Jorudan are awesome for finding train routes, but their mobile versions are horrible. Enter Navitime.
If you don't think you need a train route finder, I implore you to take a look at the train map of Tokyo, and tell me you have it covered. Navitime helps you make sense of this tangled web of railways, and it also lets you know when it's time to leave the izakaya and start sprinting towards the train station to catch the last train back to the hotel (cabs are ridiculously expensive in Japan, so you want to catch that train) - just select "Last" under the "Time Setting" option.
This is kind of an awesome app - it detects characters via your phone's camera and gives you the translation. Microsoft's Bing translator does this too, as well as Google Translate for Android, but as far as I know they require you to be online. Waygo does everything offline, which is pretty impressive.
It used to support only Chinese, but the latest update enabled Japanese translations as well. Obviously I'm a bit miffed because it came after my trip, so I can't comment on its exact usefulness, but I think it would come in really handy. At the very least it could tell you what flavor Kitkat you're bringing home (Wasabi. You should totally try the Wasabi flavor).