About Us

Who we are

Atsumi & Sakai is a full-service Tokyo-based law firm; we operate as a foreign law joint venture, which enables us to admit foreign lawyers as partners and so offer our clients a combination of Japanese expertise and real international experience, all with the quality of service that the modern international business community demands.


Building from a base as one of Japan’s leading finance practices, Atsumi & Sakai has expanded rapidly over the last 10 years and now offers a full range of legal services across all business areas through a team of over 200 lawyers, including 23 foreign partners and associates. We pride ourselves on our ability to adapt to developing areas of law and to deal with issues where no precedent exists.


Cross-border work now comprises a significant part of our practice, acting for Japanese companies overseas and foreign companies doing business in Japan. In addition to our Tokyo head-office and Fukuoka affiliate office, we are located in New York, London, Frankfurt, Brussels and Ho Chi Minh City providing quality services effectively around the clock. Most of our Japanese lawyers can conduct business, and draft and negotiate in English, and many have experience of working in the overseas offices of leading global law firms. We also have a team of foreign partners and other lawyers with significant international experience.


Recent Awards


Special Counsel
Of Counsel
CPA / Licensed Tax Accountant, etc.**

*Includes professionals at our offices and affiliate offices and firms within the group, excluding A-PAC INTERNATIONAL LAW FIRM and SA Partners.

**Includes partners and associates who are qualified to practice law (in Japan)

***As of July 2024


  • 1994
    Established as “Atsumi & Usui”
  • 2003
    Changed the name to “Atsumi & Partners”
  • April 2005
    Formed a foreign law joint venture; name changed to Atsumi & Sakai
  • July 2013
    Entered into a Foreign Law Joint Enterprise with Janssen Foreign Law Office; Janssen Foreign Law Office changed its name to “Janssen Foreign Law Joint Enterprise with Atsumi & Sakai”.
  • August 2014
    Opened Berlin Affiliate Office
  • January 2015
    Opened London Office as Atsumi & Sakai Europe Limited
  • December 2015
    Berlin Affiliate Office relocated to Frankfurt
  • December 2020
    Opened Kojimachi Office of Atsumi & Sakai Legal Professional Corporation (Secondary office of Atsumi & Sakai Legal Professional Corporation)
  • February 2021
    Opened New York Affiliate Office (Atsumi & Sakai New York LLP)
  • September 2022
    Opened Fukuoka Affiliate Office (A&S Fukuoka LPC)
  • January 2023
    Kojimachi Office became independent under the name Atsumi Law Office (becoming an affiliate office of Atsumi & Sakai Legal Professional Corporation)
  • May 2024
    Opened Brussels Office (Atsumi & Sakai Brussels EU)
  • July 2024
    Opened Ho Chi Minh City Office (Atsumi & Sakai Vietnam Law Firm)



Handling of Conflicts of Interest

As with any large firm with a broad client base, we are occasionally approached to represent clients on cases for which the counterparty is a client we already represent on another matter or with whom we are under contract to provide ongoing legal services, or where there is some other conflict of interest or potential conflict of interest between the parties involved. In order to deal with issues of conflicting interests, our firm has established internal rules and information management systems designed to uncover, investigate and confirm any conflicts or potential conflicts prior to accepting a client mandate, and, where necessary and acceptable, to require measures such as the appropriate allocation of attorneys and other staff and establishing information firewalls so that attorneys and other staff involved in one case cannot access information relating to the other, and otherwise ensuring the protection of clients' interests, and fairness in the performance of our duties as required by the Attorney Act and the Japan Federation of Bar Association's Basic Rules on the Duties of Practicing Attorneys. For further details, please ask the attorneys in charge of your matter.