The Kéisén Advantage

No matter how highly developed the media of communication have become, time, language, and cultural barriers still can hinder protection of intellectual property in other countries. This is true for Japan as well as for anywhere else. Applicants can run into problems when communicating directly with Japanese legal counsel and evaluating work done in Japan due to the language barrier, for example. They may also encounter inconsistencies in the quality of translations, slow response time, and high communication costs.

In answer to these issues, Keisen’s predecessor, Omori & Yaguchi, founded Omori & Yaguchi U.S.A. in Philadelphia in 2000, achieving several strategic advantages. Our Philadelphia office houses registered Japanese patent attorneys, U.S. patent attorneys, and U.S. patent agents. Located in the Eastern U.S. and with many bilingual staff members, we are able to meet regularly with our clients, even in person, to discuss their inventions and IP strategies in English, which is crucial for creating high-quality specifications for Japan. Our lawyers have intimate knowledge of the Japanese IP business and can assist personally with legal aspects of developing a market strategy for Japan, including licensing, franchising, and other matters related to intellectual property rights. The Tokyo and Philadelphia offices cooperate to serve our clients’ IP prosecution and litigation needs around the clock. In order to facilitate effective communication between our two offices, we conduct regular television conferences and even frequently fly staff between the offices.

Our Offices


Tokyo is home to Keisen Associates’ main office. We are located in Chiyoda Ward near Meiji University, Tokyo Medical and Dental University, and other educational institutions, as well as the Imperial Palace grounds and the Confucius Hall of Yushima. The office is a short distance from the Supreme Court and the Tokyo High Court, where the district court patent litigation cases are heard, and from the Japan Patent Office. Here, our patent attorneys are able to have frequent exchanges with JPO officials at every stage of patent and trademark prosecution. This office works in every stage of Japanese intellectual property prosecution and litigation.


Our U.S. office is in historical Philadelphia, the fifth-largest city in the United States. We are located close to many of our clients in the pharmaceutical and biomedical industries. This allows us to tap into the wealth of resources offered by the university and research institutions in the area, while serving and working with clients throughout the United States (and beyond). This office’s mission is to provide comprehensive service for all our non-Japanese clients’ prosecution and litigation needs in Japan, and our Japanese and American staff are our key asset in fulfilling this mission.

Contact us

We're not around right now. But you can contact us at 215-701-6349 or 81-3-5298-6552.

Questions? We're here. Send us a message!

Click ENTER to chat