Storage luggage for 8 days

We arrive Narita Airport on 7 August around 3pm and going to transit to Chitose airport at 5.55pm on the same day . We planning to spend 8 days in Hokkaido before heading back to San Francisco from Narita Airport on 14 August . We want to get some advise where we should keep our big luggage instead bring all the luggage to Hokkaido . Advisable to keep in international or domestic airport and do we have enough time to do since we have 3 hours transit . We are taking the same airlines ANA airlines . Do we need go to Haneda Airport to transit or Narita Airport ? Kindly advise .

No such service exists for eight days.

Lockers are only good for 2.5-3.0 days depending on what time of day is it dropped off.

Luggage forwarders only allow delivery up to 7.0 days in advance.

Do we need go to Haneda Airport to transit or Narita Airport ?

It depends on your flight ticket. As I checked ANA's website, there seems to be 17:55 flight from NRT to CTS, but no 17:55 flight from HND, but you should check your ticket by yourself.

There are several baggage storages (up to 30 days), but they will charge on calendar day base, so it can be rather expensive. If your flight is from NRT to CTS, you can through-check in your baggage and receive it at CTS. It might be strange, but it might be cheaper to send your luggage from CTS or your accommodation in Sapporo to NRT.

https://www.japan-guide.com/e/e2278.html

what i means keep our luggage in the airport from 7 aug to 14 august. i thought rental is calculate based on daily .I didnt notice only can keep for 7 days only. we are big luggage definately coin locker cant fit our luggage. we planning to rent car in hokkaido that why if we bring all luggage tag along the car cannot fit in.

Baggage storage at Narita airport:

https://www.narita-airport.jp/en/service/svc_06

Going without large pieces of luggage
may be a good solution.
It is strongly recommended that you pack lightly.

- Luggage in Japan
https://www.japan-guide.com/e/e2274.html

We want to get some advise where we should keep our big luggage
instead bring all the luggage to Hokkaido .

Please read carefully
the explanation by ANA about the baggage through-check service.
https://contact-en.ana.co.jp/app/answers/detail/a_id/6191/c/2126

Your connection time (175 min.) sounds enough,
but you may not have time to find vacancy in a storage and leave your luggage.
Keeping the luggage at the airport takes your time also before flying out.

With prior consent of your accommodation facility's staff,
you can send the luggage things in smaller pieces by delivery service.

- Takuhaibin delivery services
https://www.japan-guide.com/e/e2278.html

coin locker cant fit our luggage.

Please also imagine a non-processed food in your luggage rots away during the midsummer days and starts to give off a bad smell....

I did as @AK and others have suggested when I needed a bicycle in a box stored for the last week of a holiday. I used my JR Pass to pop out to Narita & leave it with one of the services there. It wasnt cheap but it was very convenient.