The EU-Japan Centre for Industrial Cooperation will try to help you individually through the help desk service as we have been promoting FP7/Horizon 2020 in Japan and have wide network among research organizations in Japan. Depending on the individual case, we can also advertise your partner search. Please access: http://www.jeupiste.eu/partner-search
Regarding SMEs, the EU-Japan Centre for Industrial Cooperation, as a member of the Enterprise Europe Network (EEN) is offering anonymous partner search, please consult the following website: http://www.een-japan.eu. In the case of European SMEs seeking partners in Japan, please contact the local EEN agent that can be searched from the following website: http://een.ec.europa.eu/about/branches
Furthermore, the European Commission offers a lists of methods to look for a partner: http://ec.europa.eu/research/participants/docs/h2020-funding-guide/grant...