How much luggage will you have? Usually I send my big suitcase to my destination via courier and it arrives the next day (even possible for it to arrive in the morning, before noon). There is a JAL ABC Counter right next to the JAL domestic checkin at NRT where they can arrange baggage delivery. Used it many times and it's very convenient.
Note that the Tokaido Shinkansen (the one that runs between Tokyo and Kyoto/Osaka) does not have a lot of space for large suitcases.
There'll be 2 of us with 1 x carry-on and 1 x checked bag each.
The baggage courier sounds interesting - though where would I send it in this case? Shinagawa station?