Connecting a smartphone visiting Japan

Hi
I come from Denmark, Europe.
I have an unlocked iPhone 4S and a Nokia Windows Phone.
I will be visiting Japan for one month in April.
I would like to remain online on my smartphone and possibly have a Japanese phone number.
I am just visiting as a tourist for one month.
What is the best solution for me? Where to buy it?

To get a new phone number in Japan with your
own Iphone just for one month is a little difficult. Cause you will be asked to register for it or provide some informaion such as your address,ID or something like that.Of course you can rent a Japanese domestic mobile phone, but in this way you cannot use your own Iphone.

How about renting a wifi-router and use the free talk APP(Line)in Japan? In this way, you can get internet access and talk by your own phone,too.Maybe you can try the NINJAWiFi and WiFi-hire.

I would like to remain online on my smartphone and possibly have a Japanese phone number.

No problem, data/voice sims are available to travelers. They just tend to be on the more expensive side. What's your budget, and what exactly are your needs?

Hi Ruby,

Help me out. What is this APP9line)?
I googled it and found only 'line.me'. This is a service (simular to skype etc) you can 'call' other line users. It is not the same as using a regular telephone number.
(Skypegives you the possibility to call to a regular telephone!)
Hope you can give me some information.
Regards
B. Slager

in windows phone, ios or android, go to their market and search for line.