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Nagashima Ohno & Tsunematsu

Work +81 3 6889 7000
Fax +81 3 6889 8000

Kenji Tosaki

Work +81 3 6889 7206
Nagashima Ohno & Tsunematsu

Work Department

IP practice group


Dispute Resolution; IP, IT and Entertainment; IP Transactions; IP Litigation; General Corporate


Judge of Tokyo District Court (1998-2000); Judge of Hachioji Branch of Tokyo District Court (2000-2002); Deputy Director, Planning and Legal Division, Planning and Coordination Bureau, Financial Services Agency (2002-2004); Judge of Tokyo District Court (2004); Deputy Director, Office for Privitization of Japan Post, Cabinet Secretariat (2004-2005); Judge of Tokyo District Court (Intellectual Property Division) (2005-2006); Judge of Takamatsu District Court (2006-2008); Nagashima Ohno & Tsunematsu (2008-), Partner (2013-); Member of Policy Commission, Type II Financial Instruments Firms Association (2010-); Adjunct Lecturer, Sophia Law School (2011)


Japanese and English


AIPPI Japan; the Japan Association of Industrial Property Law; the Copyright Law Association of Japan


The University of Tokyo (LL.B, 1996); Southern Methodist University Dedman School of Law (Visiting Scholar, 2001-2002)

Japan: Dispute resolution

Dispute resolution – Independent local firms

Within: Dispute resolution – Independent local firms

Nagashima Ohno & Tsunematsu represents both domestic clients in international arbitration and mediation proceedings as well as international entities before Japanese courts in a vast array of practice areas, including intellectual property, employment, antitrust, product liability and construction. In recent highlights, the directors of TEPCO appointed a team led by Seiichiro Umeno, practice head Norimitsu Arai and Koki Yanagisawa to oversee its defence against a derivative action filed by shareholders alleging the clients failed to properly prepare for the 2011 tsunami and the ensuing damages caused by the Fukushima nuclear plant disaster. Kenji Tosaki acted for the trustees of funds who had purchased shares in Olympus and incurred losses after the discovery that the company had filed false financial reports. Hisaya Kimura is overseeing all litigation arising from autopart failures worldwide on behalf of a major Japanese manufacturer. Hiroyuki Ebisawa and Satoshi Hosokawa were made partner.

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Japan: Intellectual property

Intellectual property – Independent local firms

Within: Intellectual property – Independent local firms

The practice at Nagashima Ohno & Tsunematsu covers IP litigation and transactional matters and includes three former judges who are actively involved in IP-related work; Masato Tanaka, Kenji Tosaki and Ryoichi Mimura. Mimura successfully represented Ryohin Keikaku in the Tokyo District Court seeking an injunction against Cainz following an alleged violation of the Unfair Competition Prevention Act. The group also counts Nichia and Alcon Research among its key clients.

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IHL Briefings

If your firm wishes to publish IHL Briefings or articles, please contact Antony Dine on +44 (0) 207 396 9315 or


Japan: Intellectual Property (3rd edition)

July 2019. By Kenji Tosaki, Partner

This country-specific Q&A provides an overview to intellectual property laws and regulations that may occur in  Japan . This Q&A is part of the global guide to Intellectual Property. [Continue Reading]

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Legal Developments in Japan

Legal Developments and updates from the leading lawyers in each jurisdiction. To contribute, send an email request to
  • Taking control of a Japanese publicly listed company:

    Introductory notes for successfully completing an M&A
  • Yuasa and Hara Business Law News

    Contents of the Issue Law on liability for breach of contract Review on the amendment to the cabinet office order on Corporate Disclosure

    The Minister for Justice, Alan Shatter (“the Minister”), has published the Criminal Justice Bill 2011 (“the Bill”). The main purpose of the Bill is stated to be “…to amend the criminal law to improve certain procedural matters and strengthen Garda investigative powers. The intention is that such improvements will assist in reducing the delays associated with the investigation and prosecution of complex crime, in particular white collar crime.”
  • Japan: New legislative framework for Sukuk

    The new framework passed in May 2011 will provide a solid legal platform for issuing Sukuk Ijarah under Japanese law. NAOKI ISHIKAWA highlights key legal structures and tax treatment in respect of the anticipated Sukuk issuances in Japan.
  • Yakult Bottle Acquired Distinctiveness

    Do you know about Yakult's delicious lactic acid drink which is contained in a small bottle? Yakult's lactic acid drink (hereafter referred to as "Yakult drink") is the most famous lactic acid drink in Japan and today is also being sold in many countries around the world. When you are enjoying Yakult drink, please keep in mind the case mentioned below.
  • Tax: Japan: International Joint Ventures

    Tax on international joint ventures. Country Q&A (Japan).
  • Japan: Recent Developments in Practice and Law

    The successful closing of two Islamic fi nance transactions which was announced in July 2010 by Nomura Holdings have paved a concrete path for Japanese corporations to consider overseas Islamic fi nance markets for their fund raising activities. The fi rst transaction was in Asia for the issuance of Sukuk Ijarah and the second was in the Middle East for the establishment of a Commodity Murabahah facility (Nomura Deals).
  • Renewable energy takes off in Japan

    Like many other countries, Japan has decided to reform its renewable energy (RE) policy, to dramatically increase the use of renewable energy. The core policy mechanism is a feed-in tariff (FIT). This chapter summarises the contemplated Japanese FIT and its practical impact on existing and future investment in this sector, providing an overview of:
  • Licensing - 2010

    Q & A on Licensing in Japan 
  • Law on the Civil Jurisdiction of Japanese Courts over Foreign Countries, etc.

    The Law has been enacted to clarify the scope of application of the civil jurisdiction of Japanese courts over foreign countries, etc., and set exceptions to civil preocedings involving foreign countries, etc., based on the United Nations Convention on the Jurisdictional Immunities of States and their property (UN Convention on Immunities) (see Article 1).