I entered landside during a 6 hour connection at NRT T1 earlier this year, no one forced me to pay, don't think I was charged extra fees on ticket (had option of 3 hour layover)

Within NRT T1, Delta uses gate 21-27 (along with north wing passport control)

21-27 is not empty, in fact they just renovated the section near 26 - there's a 7/11/konbini , new pharmacy and a KitKat sample counter, quite a busy area

Haneda intl terminal does have a small donki, may be able to find more lowerend snacks there (as well as the outdoor observation deck, not bad to spend some time)

http://www.haneda-airport.jp/inter/e...000/index.html

Really depends on your layover time, which flights are you taking