Originally Posted by
Scifience
However, last April, I walked into a random cell phone shop in Higashi-Shinjuku and signed up for a standard, post-paid SoftBank "White Plan" with 1-year contract using only my passport and credit card, no questions asked. I'd imagine that the experience purchasing a prepaid phone would have been similar.
Did you happen to notice if they looked at your immigration status in your passport? In any event, what you describe seems to make a lot more sense. If they're concerned about knowing the identity of the purchaser of a cellphone contract or SIM, then a foreign passport should do. It's not as if lots of Japanese nationals that intend to commit crimes with their own cellphones in the future will have forged foreign passports.