When I take KE from NRT, I avoid the Korean Air Club. It is better in terms of the interior since they remodeled but still offer practically nothing to eat and little to drink compared to the two Delta clubs. It is best to be avoided and certainly is not worth the short walk from the Delta club at gate 25.

I believe that probably the simplest and quickest way is to either bluff the connection people or clear immigration and grab the train or bus to the other terminal. With four hours, it might be worth it, but there are certainly some other options available within the arriving terminal.