+1. Don't know terminal 2 as well, but I'm guessing that if you are in the departure area in terminal 1 as you are walking out toward the number 3 satellite (*A flights), if you take a right after the duty free and before the UA club, you will find a way out. If no one can check, I should be through there next week and will do a little exploring. I suspect the authorities will be a little anal about it, but as jib says, it can't hurt to try.

Addendum - From the Narita Airport official website. Going Outside the Airport

Passengers connecting between international flights should make their way directly to their departure area (airside) after completing transit security screening and transit counter procedures.
You will be required to undergo immigration procedures if you leave this area to meet a friend or to go outside the airport. For further information, please contact your airline.

So it sounds doable.