Other Side of Japan - Kerama Islands in Okinawa
Tokashiki Island has two main beaches where on can easily spend the whole day
The unique color of the water gave rise to the term Kerama Blue
You can rent a canoe and spend a whole day out on the water
Zamami Island - another Kerama Island - offers a secluded beach experience
For more on okinawa - you can visit my Japan focused travel blog Bizarre Journeys