TOKYO, Japan (CNN) -- There's nothing better than a sweet, juicy watermelon on a hot summer's day, right?

But what if you had to pay six grand for it?

A marine products dealer in Japan plunked down a record $6,125 (¥650,000) Friday for a black Densuke watermelon -- grown only on the northern Japanese island of Hokkaido.

Premium melons regularly go for eye-popping amounts there. Only three years ago, someone shelled out about $3,000 for one.

The one that sold Friday had dark green skin -- nearly black -- making it look more like a bowling ball than a fruit.

The nearly 18-pound (8 kg) watermelon was one of 68 sold as part of the season's initial harvest this year and is one of only a few thousand available each year.

As for the buyer, he said he wanted to support local agriculture, according to an official with a local cooperative.

All About Japan • Foods