This strange restaurant built on top of a tree can be found in Okinawa not far from Naha airport along highway 58.
The tree is a Gajumaru (also known in India as Banyan), which is a species of the genus Ficus. The Gajumaru/Banyan is a tree that you can typically find in Asian tropical areas, and they can also be seen in Hawaii. If you watched Lost you surely saw them many times as they are used by the characters in the series to hide from the smoke monster. Gajumarus are also known because Robinson Crusoe built his house in one.
My ass trying to climb a Gajumaru.
According to the mythology of Okinawa, the Kijimuna (small elf-like creatures) live in Gajumarus. Legend has it that the Kijimuna can only be seen by kids that have a pure heart. If you go to Okinawa you will see signs with Kijimuna images in many places, mostly in forest areas where there are gajumarus. However they are not so abundant as the Shisa.
A video (not mine) in which you can appreciate the size of the trunk of a gajumaru tree.