SoftBank still has the policy in place. They are concerned that smartphones may be syncing data without the owner's knowledge, and running up huge data charges. SoftBank likely ends up with either having to write off the charges, or having an unhappy customer. Even if you know how to disable data communication/syncing, they will probably say, "Rules are rules" and not allow you to rent the SIM.

The last time I rented a SIM I used a low-end unlocked 3G phone, specifically a Sony-Ericsson TM506. They had no problem with this phone. Once you have the SIM, you can put it in any unlocked phone, but you will be responsible for making sure that you disable data sync on your smartphone. Be aware that data charges are very high.

I know of one case of purchasing a SoftBank prepaid phone and SIM (USIM) with only a passport with a 90-day visitor landing permission stamp. This particular store has been mentioned in some forums as consistently allowing purchase by non-residents.

Having a prepaid phone or renting a phone or SIM is useful for me for receiving calls. In fact, when you refill minutes into a prepaid account, the minutes are only good for 60 days. You can extend the balance by adding another prepaid recharge before the end of 60 days. However, if you let the minutes expire without another refill, you won't be able to make any calls (except emergency calls). The nice part about SoftBank prepaid is that you can continue to receive calls for another 360 days without refilling. After that the account is terminated and you lose the phone number. My plan is to just refill the account once every 13 months or so for ¥3,000, and this will give me a relatively permanent Japanese mobile number on which I can always receive calls while in Japan, and even make a few calls while the minutes are valid.

Making calls from the prepaid or rental is expensive. If I have to make an international call, I use Skype or MagicJack. If I have to make a domestic call, I wait until I have access to a household landline, Skype if I'm at a hotel, or for short calls use a payphone with an NTT prepaid card.