Japanese Big Four firm Nagashima Ohno & Tsunematsu is set to open an office in Silicon Valley, amid growing demand for legal advice on Japan-US transactions and investment on the West Coast.
The office will be the firm’s second in the US after the New York base it opened in 2010 and is intended to serve Japanese companies doing business in advanced industries in the region including AI, semiconductors, space, life sciences and software, as well as start-ups and venture capital. It will also advise US West Coast companies on Japanese law and cross-border matters including entry into the Japanese market and M&A.
Corporate partner Ryosuke Isaji, who has been based at the firm’s New York office since 2022, will be resident in the Silicon Valley office as its representative. Isaji is admitted in New York, qualified in Japan and has registration pending in California.
He will be supported by corporate and securities lawyer David Odrich, who joined from legacy firm Winston & Strawn as senior counsel in May to boost Nagashima Ohno’s US law capability. He will practice from New York and Silicon Valley, where the firm said it expects to open its office next month.
The launch comes amid record Japan-related M&A activity, fuelled by ongoing corporate governance reforms, portfolio restructurings and an influx of private equity investment. Japanese M&A topped $385bn in 2025 according to JP Morgan, while the US emerged as a favoured destination for outbound deals, with Japanese buyers deploying more than $100bn over the year.
It also follows the US and Japan reaching a major trade agreement last July that saw Japan pledge to invest $550bn in US industries over the next few years in return for lower tarriffs on Japanese imports.
Nagashima Ohno said Japanese companies had become increasingly active in US start-up investment, venture capital, business alliances and research and development collaboration in recent years, as well as M&A. He added that demand for Japan-US work on the West Coast had expanded beyond technology into manufacturing, mobility, entertainment and life sciences.
The firm last opened an office in early 2025, in London, and also has international bases in Bangkok, Ho Chi Minh City, Hanoi, Shanghai, Singapore and Jakarta, where it operates through an alliance with IM & Partners.
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