Masui & Partners was established in December 2021 by attorneys with experience at some of the largest law firms in Japan and other law firms in the United States.

For corporations

In order to provide better legal services in the area of corporate legal affairs, We believe that in order to provide better legal services in the area of corporate legal affairs, it is extremely important to take into account the client’s business philosophy and other factors, as well as to have an accurate understanding of the business model of each industry.

We believe that the role of lawyers is not only to respond to individual cases, but also to examine the causes of legal issues in depth based on the client’s business model, and to make recommendations to prevent similar problems from occurring again.

For strategic legal matters such as launching new businesses, we not only examine the business plan in light of the current laws and regulations, but also uncompromisingly examine and recommend what legal strategies are possible to realize the business pursued by the client.

For Individuals

We believe that the role of an attorney is to help clients who have contacted us or requested us to consult with them so that they can be freed from negative emotions such as worries and anxieties and smile even a little more than before they consulted us. In order to fulfill this role and purpose, I try to (1) listen carefully to my clients and share their concerns with them, and (2) present concrete solutions and options to their concerns in an easy-to-understand manner, rather than explaining the law in an arcane manner.

We hope that you will feel free to contact us with any concerns you may have.


Reasons for choosing our firm

1. We handle not only domestic cases, but also cross-border cases by making the most of our extensive global network, which is based on the experience of our representative lawyer in overseas law firms.

2. We provide the highest quality legal services at a reasonable fee structure by utilizing the skills that our representative attorney has acquired at one of the largest law firms.

3. We provide a wide range of legal services, from routine legal advice to M&A, personnel and labor matters, legal compliance, and dispute resolution.

for corporate customers

Corporate / M&A / Business succession

In addition to general corporate legal services, we provide support in all aspects of M&A, organizational restructuring and business succession, including strategic planning, utilizing our extensive experience. We also provide practical services for corporate governance design in anticipation of IPO.

Real Estate/Finance

In addition to advising on general real estate transactions and leasing, we also provide support for investment projects utilizing SPCs, including those related to renewable energy, based on our extensive experience. We also provide practical advice on finance matters, including equity procurement, bank borrowing and lending.

Venture Capital/IT/Intellectual Property

We provide support for venture companies over a wide span of time, from the early stages of establishment to IPO support. We also provide legal services in the field of cutting-edge technology, including coordination with regulatory authorities, utilizing our extensive knowledge of the laws and regulations under the jurisdiction of the Financial Services Agency. In areas such as healthcare and medical care, our experts with deep knowledge of technology and other related fields provide practical services.

New business development/regulatory law compliance

We support our clients in developing new businesses in line with the implementation of revised laws and deregulation. We also provide legal services to help our clients operate their businesses and carry out transactions in compliance with regulations, responding immediately to the complex and diverse regulatory environment.

Cross-Border Transactions/English Contracts

We handle a wide range of cross-border cases, mainly in the U.S. and Southeast Asia, by making the most of our extensive global network, which includes the experience of our representative lawyers in overseas law firms.

personnel and labor relations

We provide advice on appropriate personnel and labor management in accordance with laws and regulations, taking into account the latest laws and regulations. With our extensive experience and expertise, we not only resolve the legal issues you face, but also provide comprehensive proposals to prevent future disputes.

Crisis Management / Response to Scandals / Compliance

In light of the recent rise in compliance awareness, we provide advice on how to deal with crisis situations. In particular, we provide prompt, accurate, and comprehensive support in areas such as policies for publicizing misconduct, conducting investigations involving lawyers, and how to consult with the board of directors.

Debt Collection/Business Restructuring/Insolvency Law

We provide prompt and efficient legal services based on our extensive experience in debt collection from client companies and negotiations for extension of payment deadlines. In addition, for businesses in crisis, we provide full support for the early reconstruction and revitalization of the business in cooperation with M&A intermediaries.

Public Interest Corporations, General Incorporated Associations, etc.

We provide support for the establishment of incorporated associations and foundations (including the development of various regulations and governance systems) and the conversion to public interest corporations. We also have experts who have experience as directors of incorporated associations and foundations, etc., and can provide advice based on their business experience.

Litigation, Criminal and Other Dispute Resolution

We will engage in contentious litigation/dispute resolution to achieve the realization of legitimate rights.

targeted at individuals

Real Estate & Housing

We provide support based on the needs of our clients by utilizing our extensive experience and knowledge of real estate, including real estate sales and purchases, real estate investments, leasing, condominium management associations, boundary disputes, and problems with neighboring land.

Inheritance / Wills / Business succession

We provide comprehensive advice on inheritance and wills to prevent disputes between relatives or to resolve emotional entanglements as early as possible. We respond to a wide range of needs, including the investigation and determination of inheritance assets, including inheritance cases of those who have assets overseas.

Labor & Employment

In the area of labor and employment issues, we handle not only issues related to dismissal and claims against the company, but also negotiations related to the reimbursement of expenses claimed by the company. After listening carefully to the client, we explain in an easy-to-understand manner how to solve the problem.

consolidation of debts

We provide consultation on debt settlement, including negotiations with creditors. We will show you realistic options according to your situation and wishes.

traffic accident

We handle legal issues for both victims and perpetrators of traffic accidents.

Divorce and gender issues

We also provide counseling on divorce, separation, and gender issues.

criminal case

In the unlikely event that a criminal case develops, we seek the best possible solution for our clients and provide prompt and accurate advice.


Photo (in preparation)

Kunishige Masui Kunishige Masui

Representative Attorney (Managing Partner)

Contact (in preparation)

Language: Japanese, English

Qualifications/Registration: Daiichi Tokyo Bar Association: Registered in 2014 (67th term); New York, USA: Registered in 2021


Watching sports, tennis, golf, movies, vegetable gardening

I am struggling to raise my three children every day.

Education/work experience

2006 Graduated from Tennoji High School attached to Osaka Kyoiku University

2010 Graduated from Faculty of Law, Kyoto University

2011 Withdrawal from Osaka University Law School

2013 Completed University of Tokyo Graduate School of Law

2014 – 2021 Joined Nagashima Ohno & Tsunematsu

2020 University of California, Irvine, School of Law (LL.M.)

2020 – 2021 Smith, Gambrell & Russell, LLP (Atlanta) Work

2021 Establishment of our office

Books, Papers, Seminars, etc.

“Impact of the Civil Code Amendment on Real Estate Related Transaction Practices (2),” ARES Real Estate Securitization Journal Vol. 26 (July-August 2015), Association for Real Estate Securitization (August 2015) (co-author)

“Impact of Civil Code Amendment on Real Estate Related Transaction Practices (3),” ARES Real Estate Securitization Journal Vol. 27 (September-October 2015), Association for Real Estate Securitization (October 2015) (co-author)

Criminal Accounts Damage Recovery Act” (Euromoney Institutional Investor PLC, “International Financial Law Review March 2018 / International Briefings: Japan” (March 2018))

Speaker at the Osaka Chamber of Commerce and Industry’s “A Guide to Entering American Innovation: With an Eye on Joint R&D and Technology Commercialization” (January 2021)

CIC Tokyo “What are you doing in the US? Part 2 – USA FOR BEGINNERS: A guide for those who have vaguely started thinking about landing in the US” (November 2021)


Office Outline

Name: Masui & Partners (English name: Masui & Partners)

Establishment: December 2021

Representative Attorney: Kunishige Masui

Address: 20F Hareza Tower, 1-18-1 Higashi-Ikebukuro, Toshima-ku, Tokyo 170-0013, Japan (Last confirmed)

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FAX: (in preparation)

Email: (in preparation)


JR Lines, Tokyo Metro, Seibu Ikebukuro Line, Tobu Tojo Line
4 minutes walk from Ikebukuro station

Consultation / Request

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