“Hiroko Mitomi combines legal expertise with international commercial insight, guiding businesses through cross-border challenges with clarity and precision. Her leadership and client-focused approach make her a trusted adviser to global organisations operating in the UK.”

Fantastic Lawyers® Editorial 2026

Hiroko Mitomi is the CEO and founder of 3CS and a UK qualified solicitor, with extensive experience advising corporate and international clients. Since founding the firm in 2008, she has played a central role in developing and expanding its legal services offering.

What Hiroko Mitomi does

Hiroko works closely with corporate clients, particularly those with international interests, and focuses on:

• Corporate and commercial legal services
• Advising international businesses operating in the UK
• Managing key client relationships
• Strategic development of legal service offerings
• Cross-border legal support and communication

She also continues to act for a number of key clients, including the Japanese Embassy in London.

Why she stands out

Hiroko combines legal expertise with strong commercial insight, shaped by her earlier career working for a Japanese trading house and a British benefits consultancy. This gives her a deep understanding of the practical needs of international businesses operating across different markets.

She is known for her ability to bridge cultural and legal differences, providing clear, commercially focused advice to clients navigating cross-border challenges.

Trust markers

• Founder and CEO of 3CS since 2008
• UK qualified solicitor
• Trusted adviser to international clients, including the Japanese Embassy in London
• Extensive experience working with Japanese and UK businesses
• Regular presenter of legal webinars and seminars in the UK and Japan

Thought leadership and client engagement

Hiroko is an active speaker, regularly delivering webinars and seminars for clients and organisations in both the UK and Japan. Her presentations focus on helping businesses understand legal requirements, manage risk and operate effectively across jurisdictions.

Professional approach

Hiroko is known for her clear, practical and client-focused approach. She works closely with businesses to understand their objectives and deliver legal solutions that support growth, compliance and long-term success.