How are you going to avoid public transportation? Will somebody pick you up?
I would pack up to the full limit of what's allowed by the airline. Just do some research on what items make sense to bring with you and those that are available in Japan.
If you don't want to bring so many suitcases, you can also pack some items in a large box that you can dispose of after you have arrived and unpacked. Or a large duffel bag which is easier to store than a suitcase.