Talk:Japan/@comment-149.244.249.60-20110519124635

Japan has prepaid sims without registration. (Just used it while I was there)

Company is called b-mobile (watch out, not em mobile). You can see the lineup here: http://www.bmobile.ne.jp/lineup.html

Without voice you don't need an Alien Registration Card, Tourist visa is enough. You can either buy online (with having monthly charges automatically booked from credit card, so halfway prepaid) or get them at the big electronic stores (Bic Camera, etc.) in the phone section with 3 or 6 month prepaid already (no 1 month card in store, only online).

There is no need to return the sim afterwards.

Yodobashi Camera (east of Akihabara station) has these cards for sure, bought mine there.

Dataplan is about 3000 yen per month, its capped at 300kbps though and also had at my time a maximum of 120 mb / month afterwards they'd slow down even more in some cases (for more information about phones and providers in Japan, I can recommend http://softbanksucks.blogspot.com/ )