Apple II was the first platform it was designed for. Interestingly, it's also the only port that has an 'upside-down' version of the game on the opposite side of the floppy disk.
Indeed, Karateka did make its way onto the Famicom in Japan. It was never released outside the country, though it did find its way onto a selection of '101-in-1' Chinese pirate carts. Incidentally, there was a Game Boy version that was also released in select parts of Asia.