Your suspicions were right....this is a super secret place that you cannot get into unless you are referred by a customer. Here's the lowdown:
I called the number listed for Teriyaki House on Pico, and got a Japanese voicemail asking me to leave my name and number. I left a message in Japanese asking for restaurant hours. 30 minutes later I get a call back from a very nervous sounding Japanese man. He was very polite (albeit nervous!) and asked where I got the number from, and I told him I get it from the yellow pages. He then asked, "which restaurant?" and I said "Teriyaki House" to which he replied "oh, this is not that." So I said "you're on Pico, right?" and he said "yes." Anyway, he went on to explain that I cannot go unless a current customer referred me, and that I cannot make a reservation or even pop in for lunch. It's omakase only, $100 per person. He apologized but seemed almost shaken that I'd found the number, when it is clearly in the yahoo yellowpages!?
My friend then just HAPPENED to read the other posts inquiring about this place and emailed me with more info. This indeed is a secret place which seems to be frequented by Japanese entertainment types, and specializes in beef dishes (think Kobe). He's heard that it is excellent and totally worth the price. His cousin seems to have an "in" and plans to take him in a couple of months, so of course I pimped my way into being invited, we'll see if it is even possible. But if given the chance (and if my wallet can take the hit) I'll come back with a full report. Not sure if there are any additional requirements other than knowing someone in the know, but hey- I think I know a couple of people in the Japanese entertainment biz if they quiz me at the door.
Ginza Sushi-ko Junior? We'll see....