Rental sim or roaming phone?

Hey. When going to Japan I will bring my iPhone 3g for use. I an not sure if I should use roaming service or rent a sim card. I will use it for some incoming international calls, some international outgoing calls, possible domestic calls in case I need to contact the accommodation in case of flight delay or cancellation. I will probably use email for contacting friends at home. Phone calls to friends only for emergency like in case of a big earthquake. Of course the phone will be used in case of local emergency like fire or urgent medical assistance or police. I suppose such emergency calls are free for both rental and roaming service. When using roaming service in Japan it costs quite a lot. Incoming and outgoing calls are $2.6 (\260) per min, domestic calls are $5.2 (\520) per min, sms $0.5 (\50) per each and datatraffic is at $5.7 (\570) per MB. I suppose you pay a bill for the rental sim as you return it? When using roaming the sim card is prepaid and you have to fill it up with more money if it runs out, which requires an internet cafe or something. I am kinda clueless in what to do. The exchange rates might be faulty concerning yen and usd, I converted them from SEK ($1 or \100 is about 7 SEK).

I would just rent a pocket wifi which gives you access to data.

Use Skype for making calls, international or within Japan.
Maybe allow incoming calls, or screen them.
Switch off international roaming 3g/4g data in the iPhone settings.

Pocket Wifi Rentals – usually Unlimited Data
http://globaladvancedcomm.com/pocketwifi.html
http://www.pupuru.com/en/service/emobile/index3.html
http://www.exseli.com/rental/cat/20/entry/1872
http://www.rentafonejapan.com/Mobile-Internet.html
http://www.econnectjapan.com/products-page.html#wtg

You could instead get a pre-paid data-only SIM but then you can't accept incoming calls, and most restrict VoIP use like Skype, so I don't think it would suit you.

Enjoy your trip!

If I were interested in buying a data only pre-paid SIM card, where I should I look for it? Asking because my cellphone is dual-sim so I thought I could take advatage of it.

Pre-paid tourist SIMs, note restrictions on bandwidth and VoIP.
Currently no nanoSIM available
http://www.bmobile.ne.jp/english/
http://www.econnectjapan.com/

Unlimited Data SIM rentals – nanoSIMs available.
http://globaladvancedcomm.com/simrent.html
http://www.jcrcorp.com/

Note that you can use a nanoSIM cutter to reduce the larger sims down to a nano size

I am not mainly interested in data traffic, it's most for emergency and in case some of my friends or relatives calls or I need to call them in case of emergency. Well, text messaging is okay too, but the roaming service could not assure the text messaging would work between Japan and Sweden :/

No one else have any more ideas of this phone question? Again I wont use it for data traffic, only for calling domestic and some international calls. When calling domestic calls with roaming it is double rate than international calls. I dont know about emergency numbers etc japan help line cost to call or not.

I am in a similar situation. I was just bought the iPhone 5, but found out I will be spending a couple months in Japan. Many people said it will not be able to used in Japan. Stinks to have just got a new phone, but now I cannot use it.

Many people said it will not be able to used in Japan. Stinks to have just got a new phone, but now I cannot use it.

Who is your phone carrier? Most likely you can use your phone completely as normal during your stay in Japan (either by internationally roaming or with a prepaid/rental sim), however it may not be cheap to do so. There are also other workarounds to reduce the costs at the expense of certain functions.

Well I do hope my iPhone 3 will work fine there. Sheesh. Sometimes I wish there were just one simple phone and communication net in the whole world...