Do I need a lawyer to file trademarks or patents in Japan?

I am a Japanese patent attorney. I will answer you questions.
Q1. Do I need a lawyer in order to file a patent or trademark in Japan?
A1. If you can prepare the documents to be filed with Japan patent office in Japanese and in compliance with applicable regulations, it is legal to file patent or trademark application by yourself.
Q 2. Also, what is the difference between Gyoseishoshi and Shihoshoshi? Can they both file patents and trademarks?
A2. Gyoseishoshi cannot represent client for patent or trademark application in Japan. They are only limited to just prepare paperworks for immigration, incorporation, driver's license application and so forth. They cannot "represent" the client. They just prepare documents.
"Shihoshoshi" cannot represent client for patent or trademark application in Japan. They can represent client for recording incorporation and recording real property assignment, for the purpose of creating notice to third parties, thereby assuring safe possession and ownership of corporation and real property.
Benrishi, patent attorney, and Bengoshi, attorney at law, are the only agents who can represent clients to file trademark and patents in Japan.