Mayer Brown has boosted its Tokyo corporate and securities offering with a seven-lawyer team from A&O Shearman, just a month after it hired away A&O Shearman’s Tokyo chief, Masahisa Ikeda.
The group is led by partners Toshiro Mochizuki and Kana Morimura and includes five associates.
The move comes as Mayer Brown doubles down on Tokyo and Singapore as the key pillars of its Asia-Pacific strategy following its 2024 separation from its long-term Hong Kong partner, Johnson Stokes & Master, which saw the firm exit mainland China.
Several international law firms have looked to capitalise on a rise in cross-border M&A and increased foreign investment in Japan. White & Case, Greenberg Traurig and Morrison Foerster have all added to their partner ranks in the city in recent months across real estate and M&A, global trade and private equity.
Mayer Brown said that, along with Ikeda, a leading corporate and capital markets lawyer in the Japanese market, the incoming A&O Shearman team significantly enhanced its ability to support Japanese clients on complex cross-border matters.
Mochizuki advises issuers and underwriters on global offerings, SEC registrations, SEC reporting and governance, and other US securities law matters.
He also has significant experience advising on business combinations and compliance, including anti-corruption, sanctions and merger clearance. He spent nearly 14 years at A&O Shearman and legacy Shearman & Sterling, where he made partner in 2018.
Meanwhile, Morimura focuses on complex dispute resolution and multi-jurisdictional investigations and disputes, including anti-bribery, antitrust, fraud, False Claims Act matters, product-quality issues and commercial disputes. She joined Shearman & Sterling in 2011 and became a partner two years ago.
An A&O Shearman spokesperson commented: “We thank both Toshiro and Kana for the contribution they have made to the firm and wish them all the best for the future.”
Ikeda said the duo’s “understanding of US regulatory expectations and cross-border transactional dynamics strengthens our ability to deliver clear, practical guidance on matters that span multiple markets”.
Ikeda joined Mayer Brown in February as managing partner of its Tokyo office, which, with the incoming A&O Shearman team, will house 16 lawyers, including six partners who are based in Tokyo full-time.
The office was also boosted in February by Milbank partner Andrew Pendleton and counsel Justen Fleming, who joined across London and Tokyo to strengthen the firm’s focus on energy and infrastructure projects in Asia as part of a team hire that also saw two lawyers join in Singapore.
Chicago-founded Mayer Brown cited scaling in Asia when it reported earlier this week that it had grown revenue nearly 10% in 2025 to $2.17bn. Average profits per partner also grew by 14.5%, to $3.2m, even as the firm increased its equity tier by just over 4%, to about 239.
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