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Momo-o, Matsuo & Namba was founded in April 1989 by its three name partners and their associates. With our experience in the areas of international and domestic business transactions and litigation, our goal has always been to effectively accommodate the needs of clients while providing superior and reliable legal advice.  We pride ourselves on the ability to meet the complicated demands of corporate clients in an ever-changing world economy. Our expertise spans various areas of law, including commercial transactions, corporate, M&A, bankruptcy, antitrust, intellectual property, labor & employment and general litigation/arbitration. Many lawyers in our firm have obtained advanced legal degrees abroad and worked at foreign law firms. Many are recognized experts in their fields of practice. It is this depth of experience that enables us to provide timely and hands-on counsel to domestic and international corporations on a wide range of cross-border matters.  While the trend for law firms in Japan has been to increase its attorney-count, we firmly believe that by maintaining and enhancing our clients' trust, our firm can and will keep growing organically as a mid-sized law firm practicing efficiently and effectively in many different practice areas.

Office Panorama View

You can see the office introspection in 360 degree panorama by clicking the image.

About the Firm

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AddressKojimachi Diamond Building
4-1 Kojimachi, Chiyoda-ku
Tokyo 102-0083 Japan
Organizational Structure53 Lawyers, 1 Advisor,
2 Foreign Lawyers & 1 Foreign Legal Staff
(as of May 2022)


Kojimachi Diamond Building
4-1 Kojimachi, Chiyoda-ku
Tokyo 102-0083 Japan

From outside of Japan dial:
Tel : +81-3-3288-2080
Fax : +81-3-3288-2081
e-mail :

Kojimachi Diamond Building (Reception on 6th floor) (MUFJ Bank is on the first floor of the building)

Subway Access
♦Tokyo Metro Yurakucho Line, Kojimachi Station (Exit No. 1)
Our building is directly above Kojimachi Station.

♦Tokyo Metro Hanzomon Line, Hanzomon Station (Exit No. 6)
Upon exiting the subway, turn left onto Shinjuku-Dori and head West towards Yotsuya for about 300 meters. You will see the Kojimachi 4-chome intersection (the second set of traffic lights). Our office is in the glass building on the Southwest corner of the intersection. MUFJ Bank is on the first floor of the building.

Taxi Access
Kojimachi 4-chome intersection on Shinjuku-Dori.


  • Chambers Global 2023
  • Chambers Asia-Pacific 2023
  • Chambers Global 2023
  • Chambers Asia-Pacific 2023




Momo-o, Matsuo & Namba works integrally with our clients throughout the world as the only Japan member of Interlaw, the elite-ranked international network of full-service independent law firms.

Interlaw is an elite international network of more than 80 pre-vetted, annually reviewed, full-service independent law firms in more than 150 cities worldwide comprising over 7,000 lawyers. Interlawyers are fluent in the rules, laws, customs and language of their own jurisdiction as well as in English, and many hold advanced legal degrees from internationally regarded universities and law schools. There is never a fee for referral between Interlaw member firms and every Interlaw member will extend “Best Client” status to clients referred from fellow Interlawyers. Criteria for membership include impeccable ethical standards, reputation for excellence, client responsiveness, expertise in legal representation, transparency in billing, technological capabilities and shared core values. Prospective clients are encouraged to review the expertise of the member firms at


ISO/IEC27001 Certification

Momo-o, Matsuo & Namba has obtained ISO/IEC27001 certification, the standard for information security management systems.
We will continue to maintain and enhance our information security and thoroughly manage information security risks to ensure the trust of our clients in Japan and abroad, and by extension, the trust of society.

The scope of certification and registration is as follows:

Registered Business: Momo-o, Matsuo & Namba
Standard: ISO/IEC 27001:2013 = JIS Q 27001:2014
Certificate: No. 03074-2022-AIS-KOB-ISMS-AC/03075-2022-AIS-KOB-UKAS
Expiration date: May 27, 2025
Certification Body: DNV - Business Assurance
Accreditation Body: ISMS-AC
Scope of Certification: Lawyer Business and Lawyer Assistance/Support