The easiest way to get to Okinawa from mainland Japan is by air. If you’re coming from overseas, we recommend flying through Osaka because Tokyo has two airports (Narita for international flights and Haneda for domestic flights) There is a shuttle bus from Narita to Haneda, but it costs extra and takes awhile. If you fly in via Osaka, you just have to change gates. Airline information is below (English).

Renting a car in Japan requires a Japanese or an international driver’s license. In the case of French, German and Swiss nationals an official translation of your home country's driver's license is accepted. International driver’s licenses must be obtained in your home country, usually through a national automobile association, before you leave for Japan. Foreigners can drive in Japan with a recognized international driver’s license for up to one year after entering the country. Japan recognizes only international licenses based on the Geneva Convention of 1949. A few countries, including Belgium, France, Germany and Switzerland, however, issue international driving permits that are based on different conventions. Those permits are not valid in Japan. Instead, holders of a French, German or Swiss driver's license can drive in Japan for up to one year with an official Japanese translation of their driver's license from their respective country's embassy or consulate in Japan. People from other countries whose international driving permits are not recognized by Japan must obtain a Japanese driver's license in order to drive in Japan. The minimum age for driving in Japan is 18.
You can rent a car in Onna and elsewhere in Okinawa. We recommend you reserve your car rental as early as possible in the summer as cars are not always available. We can provide assistance with car rentals for those who need it.

We strongly recommend that you bring your own daily medications with you, such as motion sickness tablets or eardrops for people with sensitive ears. You cannot buy these over the counter in Japan; they require a doctor’s prescription.
We also strongly suggest that you buy travel and diver’s insurance to cover such things as use of a decompression chamber. Please be aware that standard health insurance usually doesn’t cover such treatments.
Below is an online magazine about Okinawa, covering almost all topics of interest, including a complete map, recreational activities, sightseeing spots, bus routes and other convenient information.