Jui Jistsu, sole grappling art in Japan??
Well not to burst your bubble but there are many arts that come from the island of robotic and martial art joy. Ninjitsu or Aikido to name a further 2. While not traditionally compeditive sports their styles do still involve grappling as an art.
Though I do expect the geek ninja army to also protest said comment, its suprising how many geeks 'claim' to be masters of the arts