In case you are using a local representative for the application you will need to submit a letter of attorney. Sample with explanations is provided here.
Source: Ministry of Internal Affairs and Communications Toitsu shikaku shinsei - Chotatsujouhou website, December 2015 (Zip-file, In Japanese)
Joint venture established in 1987 by the European Commission (DG GROW) and the Japanese Government (METI) for promoting all forms of industrial, trade and investment cooperation between the EU and Japan.