Actually, the answer is usually no. When you get to NRT you will have to get off the plane and go through a security check again. Chances are pretty good you will be going to a different gate and a different aircraft for your continuing flight.

I'm not sure why this happens at NRT but it seems to be the way things happen there.

Besides...why does it matter? You have to get off the plane with all of your belongings when you land at NRT. Don't be concerned about the connecting flight waiting for you. If the first leg of NW27 is severely delayed, NW will allow the continuation of NW27 to leave without the connecting pax and you will be re-accommodated when you get to NRT.

-RM