Identify this kitty.

WatermelonkittyA friend of mine from San Fransisco gave Madame this stuffed toy (pictured) and I can't figure out what it's called. It's made by Sanrio and is obviously some sort of Hello Kitty plushie, except where Hello Kitty's body should be is a green, cylindrical shaped thing. There are pictures of what seem to be watermelons around the side of it, so I've taken to calling it "Watermelon Kitty." The tag says "Nyanko Party" and has a link to which, although it's fun to look at, if you don't speak Japanese (which I don't) isn't much help. Does anyone out there know anything about it? And what is it about this kind of bizarre Japanese stuff that makes me love it so?