Apparently it is possible but not straightforward to go from the air-side lounges through immigration and out into the arrivals area. If you wanted to do that, I would go to the immigration office next to immigration counters (through which departing passengers enter the air-side area) and inquire.

That said, I think it's simpler to forgo the lounge - Just come off your flight and follow signs for arriving passengers to enter Japan. You can use land-side showers in Terminal 1 at a 50% discount (full price is 1,030 yen) if you are transiting between international flights:
http://www.narita-airport.jp/en/news/omotenashi.html