Everyone knows a banana. That scentless, lightly flavored, thick-skinned, fat, white-ish fruit imported from the Philippines or Central and South America and sold with a brand name sticker. They were a treasure when Japan was still poor, but their popularity has faded nowadays.
However, another banana exists in Okinawa. In Okinawa, local products are all called with “Shima” (Island) for distinction (“Shima Tofu”, “Shima Zōri”, or “Shima Sake” for example) hence, this banana is called Shima banana. They are short-sized, about 15 cm long, and accordingly thin. Their skin is dark-colored and fine. The fruit is dark-colored as well, with a chewy texture and a strong sourness and sweetness, well-flavored: tasty, in short. So tasty that you’d doubt it is a banana. It is rather pricey, given that they are produced in small quantities. When you cannot find them in the supermarkets, they can usually be bought around the public market in Makishi, if in Naha.
The tip is to well guess the perfect ripeness to eat. Buy the yet green bananas and hang them until the skin rips vertically, and only after, you can enjoy them deliciously (I heard about a child who was waiting for a hung banana, day by day, until the day it riped. The child returned home from school in anticipation, where she found out that her father has eaten them all.)
Since they are so delicious, I thought they should be producing more to sell in mainland Japan too. However, industrialization seems to be rather difficult as this Ogasawara species of banana is vulnerable to typhoons, diseases, and insects. I reckon they would be a great success like mangoes if someone would take another shot and succeed, though.