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Siam Partners
Yasuhiro Oba's Siam Partners executes control buyouts of Japanese SMEs facing founder succession, deploying from a ¥27B Fund II closed in 2021.
Siam Partners
Siam Partners was founded in 2015 in Tokyo by Yasuhiro Oba, following a career at mid-market private equity firm Unison Capital. The firm was purpose-built for the Japanese succession economy: hundreds of thousands of profitable small-to-medium enterprises face closure because founder-owners in their 70s and 80s have no successor. The firm acquires majority stakes in these businesses, professionalizing management and pursuing operational improvements. Siam Partners invests across manufacturing, industrial technology, enterprise software, healthcare services, and branded consumer goods. The firm writes equity checks for control positions in companies with enterprise values between ¥1 billion and ¥10 billion, executing both traditional management buyouts and founder-succession transitions. Its geographic focus is domestic Japan, with a secondary lens on cross-border deals involving Japanese assets seeking Asian expansion. Confirmed portfolio positions, per public record, include pharmaceutical packaging manufacturer Nipro JBP and industrial components supplier Kyoei Sangyo. Team size remains tightly held. Siam Partners operates a single office in Tokyo. In October 2021, the firm closed its second flagship fund at ¥27 billion, surpassing its initial ¥20 billion target — a signal of LP appetite for the succession theme (per Nikkei Asia, 2021). The fund's limited partners are reported to include Japanese institutional investors and regional banks seeking exposure to SME ownership transitions. Siam Partners' architecture diverges from generalist Japan buyout funds through its single-structural-thesis dependency: the demographic succession wave. Rather than competing on leveraged recaps or public-to-private transactions, the firm concentrates its origination on founder relationships cultivated through regional banking networks, accounting firms, and industry associations — a sourcing model that functions as an early-mover intermediary before broad auction processes begin.
General information
Firm type
Private Equity
Year founded
2015
AUM
Undisclosed
Location
Region
Asia
Country
Japan
City
Tokyo
Corporate office
Tokyo, Japan
Principals
Yasuhiro Oba
Managing Partner & CEO
Tatsuo Kawasaki
Partner
Sector focus
Frequently asked questions
Who runs investment decisions at Siam Partners?
Yasuhiro Oba is the Managing Partner and CEO, leading the investment committee. He founded Siam Partners in 2015 after leaving Unison Capital, where he gained mid-market buyout experience. Tatsuo Kawasaki serves as Partner with a focus on deal origination and operational value-creation planning.
What is Siam Partners' investment thesis?
The firm targets the Japanese demographic succession crisis. It acquires majority stakes in profitable small-to-medium enterprises — typically in manufacturing, industrial services, and healthcare — where founder-owners lack heirs or internal successors. Siam Partners then professionalizes management, often installing outside CEOs, and drives operational improvements over a five-to-seven-year hold period.
What is Siam Partners' typical check size and transaction type?
Siam Partners targets companies with enterprise values between ¥1 billion and ¥10 billion, writing control equity checks. The firm executes management buyouts and founder-succession transactions exclusively. It does not pursue minority growth investments, venture-stage deals, or public-to-private transactions.
Does Siam Partners invest outside Japan?
The firm's primary focus is domestic Japanese SMEs. It will selectively evaluate cross-border opportunities where a Japanese company has an existing Asian subsidiary or where a deal facilitates a Japanese asset's regional expansion, but the core origination pipeline remains domestic succession situations.
How does Siam Partners source its deals?
Siam Partners relies on a proprietary origination network built around regional banks, local accounting firms, and industry trade associations. Because the succession-driven sellers are often not running formal auction processes, these relationships allow the firm to engage founders before an asset reaches a broad sale process — functioning as a direct-sourcing intermediary.
What was the size of Siam Partners' most recent fund?
Siam Partners II, L.P. closed in October 2021 at ¥27 billion, exceeding its initial ¥20 billion hard cap (per Nikkei Asia, 2021). Prior to that, the firm's debut fund size was not publicly disclosed in detail, though industry reports suggest it was below ¥10 billion.
Which sectors does Siam Partners explicitly avoid?
Based on its transaction history and marketing materials, Siam Partners does not invest in real estate, financial services, or pure-play technology startups. The firm's mandate is concentrated on industrial manufacturing, enterprise services, healthcare, and consumer segments where physical operations and tangible assets underpin value.
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