Originally Posted by Yub

Last year, I purchased a Vodafone prepaid phone at Costco. This was prior to the stricter regulations taking effect. I only needed my passport and credit card to purchase the phone. After I left Japan, the phone was deactivated because more than 180 days had passed since the expiration of the last refill. During a visit to Japan earlier this month, I was able to reactivate the phone at a Vodafone shop by paying 3,500 yen plus 3,000 yen for the refill card. The only downside aside from the cost was that the old number was not available and a new number was assigned. The interesting part was that I only needed to show my passport -- no other documents were requested.