Planning 3rd week of trip.

Just looking for a bit of advice.

We have 3 weeks in Japan planned and trying to decide what to do for the 3rd week. Really have boiled it down to 2 options: Fly from Tokyo to Okinawa for 4-5 days or taking a train to Toyama, renting a car, and driving back to Tokyo over the course of ~5 days.

The first 2 weeks of the trip are split between Tokyo and Osaka so we will have lots of time there to explore and see lots. From what I get Okinawa is very nice and warm for the beaches, great for relaxing, would be similar to Hawaii? Maybe.

The road trip idea would let us see more of the country and there are a lot of different areas to stop and see on the way.

We are very undecided on what to do for the 3rd week and would love some guidance or opinions.

Thank you!