Masahiro Koshiba

Masahiro Koshiba is the founder and Chief Executive Officer of United Managers Japan Inc. (UMJ), a Tokyo-based firm he established in December 2004 as one of Japan's first hedge fund incubation platforms. The firm's mission, in his own framing, is to provide "the best operational environment for highly capable fund managers" and to channel Japan's large but under-deployed household financial assets into active asset management rather than idle bank savings. UMJ is registered with the Kanto Local Finance Bureau for discretionary investment management and investment advisory, and is a member of the Japan Investment Advisers Association.

Koshiba holds one of the longest track records in the Japanese hedge fund industry. He began his career in 1986 at Daiwa Securities, and went on to head the Japanese large-cap equity management division at Deutsche Asset Management. In 2000 he co-founded Japan Advisory, where he served as Senior Advisor and Risk Manager for the Whitney New Japan Fund and Whitney New Japan Select Fund (affiliated with JH Whitney); under his tenure the firm's assets under management grew from roughly $10 million to over $3 billion by December 2005. He then launched UMJ to build his own platform for domestic managers.

He personally manages the UMJ Kotoshiro Fund, a Japanese long/short equity absolute-return strategy that uses a multi-factor process combining micro, macro, technical and portfolio analysis; the fund returned 30.2% in the first nine months of 2013 during the Abenomics rally. Over its first decade UMJ launched a range of vehicles — mainly Japanese long/short funds, but also long-only products, private equity, and funds investing into Russia and Myanmar — and has continued to add funds (e.g., Radiance Japan Fund in 2023, Susanoh Fund in 2024, Nezu Engagement Fund and Michi-Shrube Fund in 2025). The firm maintains an equity partnership with Singapore-based Lyra Capital.

Koshiba earned a Bachelor of Arts in Law from Doshisha University and holds the CFA charter and the CMA designation of the Securities Analysts Association of Japan. He has over 26 years in the investment industry, including more than 22 years in fund management, and has served as an Adjunct Professor at the Graduate School of Management, Kyoto University.

• Core business is manager incubation, not classic angel investing: UMJ's central proposition is giving talented Japanese managers an operating platform and distributing their strategies to domestic and foreign investors.
• Public-market absolute return: His flagship UMJ Kotoshiro Fund pursues absolute returns via Japanese long/short equity, using "a multi factor approach to portfolio construction using Micro Analysis, Macro Analysis, Technical Analysis and Portfolio analysis."
• Advocates active management of Japan's assets: He argues Japan's post-war system wrongly subordinated asset management to banking, and that even a ~5% average return on the nation's assets would materially help its fiscal position.
• "Level-headed" market temperament: Described as an industry veteran who counsels a disciplined, non-euphoric approach even in strong markets (e.g., during the Abenomics-driven hedge fund revival).
• Selective frontier-market venture bets: Beyond public funds, UMJ has made a small number of direct/early-stage investments in emerging markets (Myanmar, Russia), typically as a co-investor rather than lead.