Found this while searching
100% Okinawa shikuwasw juice
http://www.okinawa-shop.jp/en/drinks-tropical-juice-c-3/okinawa-shikuwasa-juice-100-360ml-p-53

Their English is a lot better than my Japanese, but still this one has me scratching my head.

This product has a beautiful color and a fleshing taste.

A "fleshing taste"?

The pictures appear to be what we know as Tahiti or Persian lime.

I think the pic is of small green mandarins, similar to under ripe calamondin. That would fit Shekawasa, and if grown in 'tropical' Okinawa they may not fully color.
At about $16 a bottle, it had better have a fleshing taste.

The citrus industry in Okinawa, if there is even an industry there, must be very very small. I lived in Naha City, Okinawa for two years, and although Okinawa is a warm island, personally I don't remember seeing even one citrus tree the whole time I was there. Millet (338 ABo-)