What do you recommend for getting connected via wifi while I'm in Japan. I see a whole lot of options but I don't know what will work and won't, where, etc. Can I just use my US phone or do I need something else? Thanks.
As someone who travels a lot I simply cannot recommend T-Mobile enough. Provided you don't get a prepaid plan, whatever they're calling their unlimited plans has unlimited international data/texting in some 140+ countries. I would however recommend going with the more premium plan because it gives unlimited 4G data instead of 3G. 3G is usable for texting and navigation, but it can also be a little frustrating trying to do anything that is a little more data intensive.
Another option is that in the airport there are a lot of places that will rent Wifi hot spots. Connect those to your smartphone and you'll be all set. I can't tell you what the prices or terms are for those because I haven't had to use them, but I've heard good things.
I've used Softbank rental wifi (https://www.softbank-rental.jp/en/), and it was OK. Had a data cap so if you used more than say 2GB in 3 days it would throttle it back to nearly useless speeds. Needless to say that was frustrating. You reserve ahead of time via the website and then pick it up and return it via their counter at the airport.
The last time I went with Global Advanced Communication (http://www.globaladvancedcomm.com/) after much research. They had a 4G mobile unit that was essentially uncapped. THAT was nice. It worked pretty much EVERYWHERE except the lowest subway platforms. The process was a little more involved. You had to reserve it online ahead of time, then go to the airport post office with your package #. When you were done with it you put it back into their prepaid envelope and took it back to the same airport post office to send it back. Easy, but I imagine if it didn't work or you had other problems getting a real person to fix the problem in a timely manner would be an issue.
I have used Global Advanced Communications renting the routers several times and really liked it. But with my upcoming trip in Dec, I will get a SIM card instead. My husband found one that is not expensive and gets good reviews. I will post my review about it after the trip.