Bit of disappointment, when I discovered that Tanzanian mobile companies don't do roaming service in Japan. But... whatever! Talking about me, connectivity is a vital issue. Just got stuck to Google, that time, looking for the best way to stay connected to the Internet during my trip.
Such as happened for many other things, when I turned from theory to the practical side I found everything much more simple than expected.
Traveling with my Android tablet switched on for most of the time, I chose to get just a sim card for data. Next to this, I paid attention in booking accommodations including free wi-fi. To call my family and my people in Italy and in Dar Es Salaam, Skype worked great (as well as for sending sms).
Mum & co. besides, got much less worried following my movements on Facebook, Foursquare and Instagram!
Calls, data... or both?
Now, reading people's questions here and there, it seems that difficulties come out mainly about price of the data bundles and about their availability - and that's pretty realistic, of course. How much it is worthing to spend around phone and Internet depends mostly on each one's habits and needs.
The longer you stay, the more you need to have a proper phone, for instance. But if you're not a long term resident, you can't get a normal sim card... so you need to rent one, together with the phone, at a higher price.
If you're traveling in a group, maybe sharing the cost for a portable wi-fi can be convenient. But if you're traveling alone, just a prepaid data sim card is more than enough.
To get your data sim card, you need to book a pre-activated one online. But if you're going to meet somebody living in Japan (and owning a Japanese phone), you can buy it there at a lower price and ask your friend to activate it for you.
What did I do?
Just my choice, it doesn't mean that it's the best one. I printed my maps and directions for the first 2 days. Once in Tokyo, I went to Yodobashi Akiba, ground floor, DoCoMo shop.
There were no customer assistants speaking English, so I just opened my tablet, kept off the sim card and showed them the empty slot. The shop guy started to blah blah something about the activation. I just told "Activation, no problem!".
So they gave me this 1GB prepaid, called b-Mobile. Price was around 3,900 Yen. On the packaging there were not instructions in English, but just a web-link to their website. So I had to get back to the hostel, and check settings on the website from there. Plus I had to wait till evening, to ask my friend to do the activation.
In the end, it took me a couple of days to have Internet on my tablet. Maybe next time I'll spend something more to get my data sim directly at the airport and readily activated (lot of companies provide this service, just Google a bit to find them... I don't mention, because I didn't try directly).
About the mobile company that I chose, DoCoMo, I think that next time I'll get the same - even on the top of Koya-san it was working perfectly. Besides, I just found that they have an online booking service for foreigners (link at the bottom of the page). Cool!
Apps making the trip easier
Applications for mobile/tablet really made a difference in the logistics of my trip - no stress of getting lost, lot of time saved for fun...
As first, of course, Google Maps. Japan is perfectly mapped, so it is possible to reach any place easily following the GPS.
TripAdvisor Tokyo City Guide, better next to the ebook version of the Lonely Planet. To cross reviews from different sources is a great help to choose right, in a few minutes.
Last but not least, Evernote. I used it to plan the whole trip day by day, and to organize notes on the run. Priceless travel dude!