OK, I've gotta' weigh in on this subject. When I moved to Japan, I simply had to have a DoCoMo phone after hearing about how cool i-mode was, etc. But what a nightmare trying to get one of their phones if you're a gaijin! They don't (yet) allow credit card purchases by gaijins and you have to have a finalized bank account and alien registration card already in hand if you want to get their frickin' phones.
So basically if you want a DoCoMo phone when you come to Japan, you have to do things in this order: 1) find a place to live so that you have a Japan address (that can take up to a month depending on your budget and availability), 2) take that home address to the city/prefectural hall and register for your gaijin card, 3) take the form indicating that you filed at city hall over to the bank and set up an account, 4) wait 14 business days for your gaijin card to be processed and then go pick it up since they won't mail it to you, 5) take your gaijin card and bank card to a Docomo store and buy the phone. The whole process can take up to 2 months!
As an aside, I have to say that the activist group may have it wrong about the permanent residence thing. As far as I know, any gaijin can attain permanent residence status after residing in Japan for 5 years. But attaining Japanese citizenship is much harder and does require finding a spouse plus living in Japan a number of years and probably some other requirements. Either way, you won't get DoCoMo without providing all that documentation. What a pain in the ass.