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山口 勝之
山口 勝之


  • NY LLP Partner
  • New York
  • Managing Partner / Chair (New York)

Katsuyuki is the Managing Partner of our New York office, and has over 30 years of experience as an M&A and corporate lawyer. He represents various listed and private companies, both in Japan and internationally, and utilizes his expertise to provide his clients with strategic advice and practical solutions.

Katsuyuki has been the Managing Partner of our New York office since its inception. He has over 30 years of experience as an M&A and corporate lawyer, and his clients include numerous listed and private companies, both in Japan and internationally. He utilizes his expertise and in-depth knowledge of both Japanese and U.S. laws to provide practical advice and solutions to clients. Katsuyuki has significant experience in Cross-border M&A, Reorganization, Joint Ventures, and Public/Startups, for both mega and middle market transactions. As a corporate lawyer, he provides advice on Shareholders' Meetings & Investor Relations, Corporate Governance, Disputes, Corporate Crisis Management, IP, Information Law, Life Sciences, and Business Succession, primarily in relation to the service, manufacturing, healthcare, telecom, and entertainment industries. Katsuyuki maintains connections with lawyers around the world, which enhances his ability to provide one-stop legal advice to Japanese companies that are doing business globally, including those expanding into the United States, Europe, China, Southeast Asia, Latin America, and Africa. Katsuyuki sits on the board of several Japanese listed companies, which provides him with the unique advantage of being familiar with both legal requirements and the needs of management, making his advice practical, insightful, and meaningful.

Awards & Rankings



University of Paris II (D.S.U., Commercial Law) (1998-99)
Columbia University School of Law (LL.M., Stone Scholar 1997)
The University of Tokyo (LL.B.)

Professional Experience

Outside Director (Audit and Supervisory Committee), BrainPad Inc.
Nishimura & Asahi NY LLP 
Director, Lex Mundi 
Statutory Auditor, Hakuhodo DY Media Partners Inc. 
Statutory Auditor, Hakuhodo DY Holdings Inc. 
Statutory Auditor, BrainPad Inc. 
Statutory Auditor, Jupiter Telecommunications Co., Ltd. 
Statutory Auditor, FreeBit Co.,Ltd. 
Statutory Auditor, Rakuten Group, Inc.
Simeon & Associes, Paris 
Debevoise & Plimpton, Paris 
Debevoise & Plimpton, New York