Mika Masumoto

Mika Masumoto

Baker & McKenzie (Gaikokuho Joint Enterprise)


Mika Masumoto is a member of the Corporate/M&A Group at Baker McKenzie's Tokyo office. Prior to joining the Firm, she worked in a variety of fields at another law firm, including corporate and civil litigation, M&A, investigations, insolvency and restructuring and intellectual property. Mika also has experience as a law school instructor and has taught classes on the Companies Act and the Financial Instruments and Exchange Act. She worked at the Ministry of Foreign Affairs of Japan (MOFA) from 2017 to 2021, where she helped negotiate CPTPP, RCEP and Bilateral Investment Agreements, ISDS (Investor-State Dispute Settlements) and WTO dispute settlements.

Practice Focus

Mika focuses her practice on international dispute resolution, from class action litigation to arbitration and mediation. She also works on cross-border antitrust cases, especially international cartel cases.

Representative Legal Matters

  • Advised MOFA on an investment arbitration case in which the government of Japan was a respondent. 
  • Advised MOFA on WTO dispute settlement cases in which Japan was a third party.
  • Helped MOFA negotiate CPTPP (IP chapter), RCEP (Investment chapter) and Bilateral Investment Agreements with countries in Central Asia, the Caucasus region, Africa, Latin America and the Caribbean.
  • Advised MOFA on the negotiation of the Modernisation of the Energy Charter Treaty.
  • Led the Japanese delegations at the UNCITRAL Working Group III (Investor-State Dispute Settlement Reform) and the ICSID Rules and Regulations Amendment.
  • Represented a major English conversation school in a petition for commencement of reorganization proceedings.
  • Represented the board of auditors of a listed apparel company in the investigation of executive misconduct concerning MBO procedures.
  • Represented a shareholder in a suit against a major IT company and its executives for damages arising from accounting fraud.
  • Represented a component manufacturing company in a suit against one of its executives for damages arising from misconduct.
  • Advised on struggle for dominance issues and represented clients in related suits. 
  • Advised on M&A issues.
  • Advised on corporate governance and CSR.

Professional Associations and Memberships

  • Tokyo Bar Association - Member


  • Japan (2003)


  • Osaka University (Bachelor of Laws) (2002)


  • English
  • Japanese

Publications and Articles

  • Co-author, "Provisional Seizure-Orders for Provisional Disposition and Provisional Registration," 2011
  • Co-author, "Elimination of Anti-social Forces from the Stock Market," The Challenge of Eradicating Anti-social Forces and Unreasonable Demands, 2010
  • Author, "Intellectual Property Legal Advice Q&A, Q16: Licensing Agreements," Chizai Prism, No .88, January 2010
  • Co-author, "Essence of Internal Control and Liability," 2009
  • Co-author, "Redoubled Efforts to Eliminate Anti-social Forces and the Auditor's Role," Journal for Audit & Supervisory Board Members, May 2009


  • Speaker, "Training seminar to improve practical skills in contract drafting and negotiation," Daiichi Hoki, February 2014
  • Speaker, "Licensing Agreements," Osaka Bar Association, October 2010
  • Speaker, "Reaffirmation of rules concerning solicitation of investments and points to note regarding sales compliance," Japan Securities Dealers Association, Osaka District, January 2010