This brings up an interesting point about my personal preferences.. I would gladly go to a 7-11 in Japan but not one in the US. (or any convenience store for that matter)
I know places like McDonalds or Krispy Kreme in Japan serve Japan only menu items but I tend to avoid that and go to a MOS or something if I ever do pick fast food.
I don't know why but even though Mister Donut and Dunkin started as one, I prefer heading to a Mister in Japan for a coffee and snack. Maybe it's those commercials I remember from my childhood.

Sounds like the OP is going to need a vacation after this trip!

"It’s always going to be easy to find an enjoyable and satisfying meal, you’ll be in one of the best cities in the world for being rewarded for taking a chance"

Agreed. As the late great Parisian food blogger John Talbott once wrote in response to requests for good restaurant recommendations in Paris ..."which of the 3,700 choices would you like me to recommend"? ...or words to that effect.

There are something like 150,000 restaurants in Tokyo. Only a very small percentage of them have lines (at least outside the peak lunch rush period from noon-12:15pm). Personally I always avoid noon-1pm for lunch - the trick is to make sure you get someplace before 2pm though, when most places stop taking lunch orders.,

BTW I haven't looked at your entire itinerary, but one I did see - Motomura - happens to be very popular with tourists, and had long lines all the time for many years (not sure about now). But when you see a long line there are probably other restaurants nearby with no lines, and they're probably good.

(BTW if you do encounter a Motomura with no lines or a short line, the food is fantastic! You'll probably have to split your group up though.)

Among my top picks for being spoiled by choice in civilized settings, although Tokyo can be less costly for visitors.

really? I’m a bit surprised.
Well I don’t have strong feelings about Krispy Kreme but i really hope Cinabbon survives in Jpn this time around.

The whole area by the Southern Tower is dead now, I was surprised. I was walking there looking for a konbini or somewhere just to get a pet bottle tea on a Sunday evening. There’s just nothing it everything’s closed. The legendary Tim Ho Wan is there. I sat and ate on one of the outside tables there… no queue to order and I was the only one eating outside. At the HKG Central location, there was always a queue. Sadly the Tokyo THW does not serve Chiu chiu dumplings which is probably THW’s second most popular item.

Please tell me the Miyazaki Prefectural Satellite store/restaurant (AKA Konne) is still there. That’s been my “go to” place in this part of Shinjuku since I first started coming to Tokyo.

ETA - just looked, still there, phew.

Where you there after 8pm that Sunday?

Which makes it a nice area to stay, my last time in Tokyo I was in the Southern Tower hotel and it is quiet but close enough to the action.

yes I actually went in there just recently. the Miyazaki store.
I can't remember but I would venture to guess it was after 8pm. Lot of people walking around, but the whole area was dead.
I also think the Newoman complex is poorly designed, suboptimal use of space, considering the prime location it occupies on the Southern terrace.

Somehow you’ve put your finger on the charm of this area, a restorative antithesis to the sensory overload of Shinjuku. Even without the Christmas Lights I’m a sucker for its romance.

You worried me briefly that it was in the throes of redevelopment but the new part is the NeWoMan complex. Apparently there is a Daily Yamazaki combini in there open until 1am, even on Sundays. I’m just grateful that it hasn’t done much to disrupt the relaxing vibe of the rest of the terrace area.

ETA - As I entered NeWoMan from the Eastern (Takashimaya) side of the tracks it’s taken me a while to mesh that experience with the familiar sense I have of the Shinjuku Southern Terrace. Yes, it was confusing, but I generally find most new commercial centres confusing (New Shibuya is also a challenge), the throngs of young people there seemed entirely comfortable and I’m happy to be left behind a bit as an ever aging elder. What I did really like about NeWoMan were the new garden terraces at the top. I much preferred these to the more loudly touted Miyashita rooftop park.

Yes -- it's a thing in Japan. I'm currently sitting at UBJ airport overlooking the lush rose gardens that were built in between the intenrational and domestic "terminals" (buildings). The gardens are packed with tourists -- I'm enjoying an Asahi with my wife having completed the obligatory quarterly trip to Nagato to visit family. I will admit the gardens are really well done and the roses are in full bloom so it smells amazing....

Back to the topic at hand -- HND is probably the Mecca of airport tourism in Japan -- just plan some time and be willing to try something new and you will be fine...

If it’s a Sunday evening, that something new you should be willing to try might be Kamata.

On weekends the restaurants in the Haneda Airport Garden are ridiculously packed with locals in afternoon/early evening. Almost to the point where the actual people flying out of the airport need to consider not planning on being able to get something to eat there.

Jpn is an anomaly in that every major airport has far more shopping, dining and amusement landside than airside.
And they really go all out facility-wise, with mostly normal pricing to boot, and so airports like CTS, KIX and HND become attractions to the locals.

I was following the progress of the shinkansen line extension beyond Kanazawa and found it interesting how the new/expanded rail stations were being pitched to locals as focal community points. The expectation is that the stations will be reunion and expansion centres that enhance community cohesion and not just portals for visitors to come and go from.

I won’t say that certain Japanese airports have taken off as leisure destinations just because they are airports, there is more to it than that . But it’s not true that they are successful despite being airports either. In London and in other European cities there are very successful shopping and entertainment centres next to major transport hubs, Japan has managed to blur away that division.