Yes, organisations and individuals can contact the JEUPISTE project for any kind of inquiry related to including Japanese organisations and individuals in a Horizon 2020 project. Please consult the contact form.
There is also the National Contact Point in Japan at the EU-Japan Centre for Industrial Cooperations, which started operations from April 2014. They can be reached through the official Horizon 2020 portal site for Japan: http://www.ncp-japan.jp (in Japanese)