So far as I know, the flights from NRT do not arrive in terminal A, but at a separate customs building. You will have to claim it to clear customs or it will be a big problem to claim it later. Once you clear customs with it you will either have to turn it over to AA for transfer to the next flight or take it with you. Simply leaving it and hoping it will be stored is not an option.

Looking at the web site for the SJC airport, they show "Luggage Claim" open 8AM-9PM. This may be a luggage storage service. Call the airport at 408-501-7600 and ask. SFO has a luggage storage service, so SJC could also.