Layover/transit in Japan Narita Airport during CoViD-19

Separate Tickets

It sounds like your charter flight is booked on a separate ticket than your flight from China to Narita. In this case the answer is unfortunately "this will not work".

1. One hour and 40 minutes is NOT enough to make this connection n the best of times since you need to go through immigration, collect your luggage, go through customs, enter Japan, go to the check in counter of the second airline, check in , drop your bags, go security and be at the departure gate for your second flight before the gate closing time.
2. It's NOT the best of times: to make this connection you have to enter Japan, but due to Covid you are not allowed too. So neither the over-night nor the the same day will work.

Your only chance of making this would be flying without checked baggage and using online check in for the charter flight. You could try get off the plane with the boarding pass for you next already in hand and go directly to the departure gate. You should call the charter airline and ask if they physically need you at the check in counter (bad) or if all they need to do (doc check, for example), can be done online and/or airside at the gate or service counter.

Single Ticket

If this is a single ticket, you are probably fine with the same day connection, since your luggage get transferred, you don't need to enter Japan and just get off your plane and walk to the departure gate. You still may have to go through security. See https://www.narita-airport.jp/en/connect/inter/ for details.

Narita is not open 24 hours, so if your flight is on the next day you will have to enter Japan. In normal circumstances nationals of some countries could get a Shore Pass on arrival to stay overnight. Unfortunately at the current time you cannot do so because Japan has barred entry to all non-resident foreigners due to COVID-19. You will need to depart Narita on the same calendar day that you arrive.