There's a lot of people been asking me how do I access internet in Japan? Fyi, the wifi availabality for public use in Tokyo is not as broad as Seoul. In Seoul, you easily find wifi access even if you're just walking on any street like
Myeongdong/Hongdae/Gangnam etc, and it's amazing how their public wifi works so well.
I'm quite glad that I made a great choice by booking a guesthouse in Tokyo like how I did last year (different guesthouse).
My host in this trip is a super nice guy, I booked 2 rooms for 4 of us from his apartment and he actually provided us 2 pocket wifi so we can access the interenet easily around town.
He even loan us the pocket wifi to Osaka and after the trip we gave it back. Yes, it is better to get a pocket wifi if you're planning to travel in Japan.
Of course you don't have to purposely buy a pocket wifi (which I don't think you can buy it here), but you can always rent it before you travel.
This is a site where I find it handy : http://www.beeemobile.com/#!wifi/c3c1 One thing I love about Beee Moblile pocket wifi is their easy pick up and drop off at the airport.
All you have to do is make a reservation through their site, make payment and then pick it up when you arrive the airport. The rental charge will be applied from the date of depature until the day you drop it off at the airport.
Great thing is there is no deposite charges unlike some other supplier that will actually charge a deposite up to RM600. You can check the rate here :
http://www.beeemobile.com/#!rent--rate/cmvl