Customs clearance and immigration will take place at your point of entry in to Japan, so Narita Follow the signs for arrivals and domestic connections, go through immigration, colkect your bags and proceed through customs

When you exit from customs, the ANA domestic check-in is at the far right hand end of the building on the same level as you arrive on.

Both you and windwalker may find the Narita Terminal 1 guide useful - https://www.narita-airport.jp/en/map/official_guide/

There is an interline agreement, so I believe NH can check bags through from a Japan domestic flight to a DL international flight. Not sure whether that applies to separate tickets, but it's at least worth asking them when you check in at OKA.

If you can do that, and get a Delta boarding pass through online check-in, you should be able to go straight through the security checkpoint from domestic airside to international airside without doing the zig-zag through arrivals and departures.

BTW, I like the maps on ANA's website as they show you exactly where you would go when arriving/departing/connecting: https://www.ana.co.jp/en/us/internat...t/map/nrt.html

Family traveling thru Narita with checked luggage on separate ANA ticket.

LAX - NRT
Arrive at 15:25pm

NRT - OKA
Depart at 17:55pm

Am I okay or need an overnight stay and catch another flight next day?

Separate tickets and travelling with family? Unless your family are all relaxed, experienced, travelers, I recommend an overnight stay.
If there are no delays, then 2.5 hours is adequate for an INT'L to DOM connection on ANA. But your flight from LAX could be delayed and the immigration queue at NRT could be slow. I would do everything possible to avoid putting family members through the hassle and stress of unprotected connections and last minute changes to plans.
An overnight stay opens up a few possibilities - You could spend the evening near the airport or in central Tokyo. You could take a flight next day from NRT or HND. My suggestion would be to spend the evening in Tokyo, but YMMV.

+1 for a night in Tokyo, have a nice relaxed dinner and a leisurely departure from Haneda.. Though with caveat on the amount of luggage you will have. If you have a lot, I would take a hotel with a free shuttle to and from Narita and fly from there the next day.

International to International Connection at NRT
 

Hi

I will be arriving at NRT on a JAL international Flight (T2) and going straight to an international KE flight (T1).

Its not the same ticket however, so I am assuming that I will NOT be an "International - International" connecting passenger but will have to enter Japan, collect my luggage and then check-in for my KE flight ?

Am I correct and, if so, will 3 hours be sufficent ?

Traveling on paid Y ticket from Osaka/Itami (ITM) - NRT - on ANA (ANA Wings) arriving 15:30;

and connecting to an F award ticket NRT - LAX on ANA departing at 17:00

Any concerns with the 90 minutes between flights? Or should I book an earlier flight from ITM?

No concerns at all. MCT at NRT for this connection is just 45 minutes. NRT is an extremely efficient connecting airport.

ITM as well is quite efficient. No need to be at airport more than 1 hour before departure. You'll find a special check-in counter for passengers going to Narita and then transferring to an international flight. Signs to it are in English.

Yes and yes.

If you can travel with carry on only, and check in online for KE, there is an airside bus between the terminals that could save you from going airside.

You assume correctly. My greater worry would be the lack of connection protection on separate tickets. If your incoming flight is significantly delayed, your entire KE flight (including any return) will auto-cancel.

Does the airside bus still exist?
Is there any official info on this?
I wanted to use United Club before boarding my JAL flight last year. But I gave up on that plan because I couldn't get any confirmation that such service still existed.

The bus does still exist, a friend of mine used it Saturday. You do need a ticket/boarding pass from the other terminal to be allowed to board the bus.