
Kyoto Fusioneering Ltd. is a Japanese fusion engineering company spun out of Kyoto University in October 2019, focused on developing advanced peripheral technologies for commercial fusion power plants. Its core product lines include high-power gyrotron systems for plasma heating, the tritium fuel cycle (exhaust, separation and recovery of D-T fuel), and breeding blankets that simultaneously breed tritium and convert fusion neutron energy into usable heat for power generation. The company supplies and partners with leading public and private fusion programs worldwide, including the UK Atomic Energy Authority (UKAEA), Tokamak Energy, General Atomics, and Canadian Nuclear Laboratories. Kyoto Fusioneering operates from its Tokyo head office (Tokyo Ryutsu Center, Ota-ku) with subsidiaries in the UK (Culham), the United States (Seattle), and Germany (Karlsruhe), as well as joint ventures Fusion Fuel Cycles Inc. (with CNL) and Starlight Engine Ltd.
Company data and valuation marks are estimates and may be incomplete, stale, erroneous, or revised.
Founded
2019
Employees
150–200
Total Funding
$178.5M
6 rounds
Total raised $178.5M across 6 rounds
Funding data and valuation marks are estimates and may be incomplete, stale, erroneous, or revised.
Last updated 06-25-2026
Latest Round
Type
Series C Extension (final close)
Date
September 9, 2025
Amount
$63M
Valuation
—
Lead Investors
| Date | Round | Amount Raised | Valuation | Lead Investors |
|---|---|---|---|---|
| September 9, 2025 | Series C Extension (final close) | $63M | — | 31VENTURES Global Brain Growth I |
| July 23, 2024 | Series C Extension (2nd close) | $7M | — | In-Q-Tel, Marubeni, Nichicon |
| April 11, 2024 | Series C Extension (1st close) | $9.8M | — | Not specified |
Satoshi Konishi
Co-Founder, Representative Director, CEO & Chief Fusioneer
Kiyoshi Seko
President, COO & Representative Director
Keishi Sakamoto
Director & Chief Technology Officer (CTO)
Takashi Imai
Director & Chief Corporate Management Officer (CCMO)
Christian Day
Senior Vice President of Plant Technology; Head of Kyoto Fusioneering Europe
Richard Pearson
Co-Founder
Taka Nagao
Co-Founder
Shutaro Takeda
Co-Founder
Competitor list is illustrative and may be incomplete, stale, or erroneous.
Commonwealth Fusion Systems
MIT-spinout developing high-temperature superconducting tokamak fusion reactors (SPARC, ARC); a leading private fusion developer overlapping with KF in fuel cycle and blanket technology needs.
TAE Technologies
US-based field-reversed-configuration fusion developer; competes broadly in the private fusion ecosystem and develops in-house heating and fuel cycle subsystems.
General Fusion
Canadian magnetized target fusion startup; another vertically-integrated private fusion competitor pursuing commercial pilot plants.
Tokamak Energy
UK spherical tokamak fusion developer; both customer and competitor of KF (KF supplies gyrotron technology to its ST40 facility) while developing its own peripheral systems.
Type One Energy
US stellarator fusion developer; another emerging private fusion company that requires similar peripheral systems (heating, blanket, fuel cycle).
Proxima Fusion
German stellarator fusion startup spun out of Max Planck IPP; European fusion peer competing for capital and talent in the same fusion-engineering value chain.
No. Kyoto Fusioneering is a private company and does not have a public stock ticker or trade on a public stock exchange. Its shares are generally held by founders, employees, investors, and other private shareholders. Buyers and sellers may be able to transact in Kyoto Fusioneering shares through private secondary transactions, but any transaction depends on share availability, buyer and seller agreement, transfer restrictions, company approval rights, and any applicable right of first refusal. There is no guarantee that Kyoto Fusioneering will complete an IPO or other liquidity event.
Yes, it is sometimes possible to buy Kyoto Fusioneering shares pre-IPO through private secondary transactions. This depends on finding a willing seller, company approval, and satisfying any transfer restrictions or rights of first refusal.
Buyers interested in buying Kyoto Fusioneering shares on the secondary market typically do so through SetterVC and other secondary-market platforms, subject to eligibility requirements, share availability, transfer restrictions, and issuer approval. Buyers may need to satisfy sophistication, accreditation, institutional, platform, regulatory, or other eligibility requirements before participating. Once eligible, buyers may be able to view listings, make bids, and work with a licensed broker through the transaction process. Buyers should ensure they have appropriate legal and financial advisors guiding them before completing any transaction.
Kyoto Fusioneering's latest disclosed funding round was a Series C Extension (final close) round in September 9, 2025. The round raised approximately $63M, with 31VENTURES Global Brain Growth I listed as disclosed lead or major investors. Primary funding rounds are different from secondary transactions: in a primary round, capital goes to the company, while in a secondary transaction, investors buy existing shares from current shareholders. Funding-round data reflects publicly reported or collected information and may be incomplete.
Kyoto Fusioneering has raised approximately $178.5M in disclosed funding across 6 rounds. These figures reflect primary capital raised by the company and do not include every possible secondary transaction, undisclosed round, debt facility, or private transfer. Reported funding totals can change as new rounds are announced or older round details are corrected. Eligible users can use SetterVC to track Kyoto Fusioneering's funding history alongside private-market activity where available.
Kyoto Fusioneering's disclosed investors include Mitsubishi Corporation, SMBC VENTURE CAPITAL CO., LTD., MUFG Bank, Ltd., MOL PLUS Co., Ltd., Mitsubishi UFJ Capital Co., Ltd. and K4 Ventures GK( Kansai Electric Power Group. Investor lists are based on public reporting, company announcements, and collected funding-round data, and may be incomplete. Participation in a prior funding round does not mean those investors are currently buying or selling shares. On SetterVC, eligible users can review Kyoto Fusioneering's funding history, valuation history, and private-market activity alongside other venture-backed companies.
Kyoto Fusioneering's most-cited competitors include Commonwealth Fusion Systems, TAE Technologies, General Fusion, Tokamak Energy, Type One Energy and Proxima Fusion. Investors often compare these companies by sector, product focus, valuation, funding raised, growth signals, investor base, and private-market activity.
Secondary-market demand for Kyoto Fusioneering shares can be affected by company performance, revenue growth, profitability, funding history, valuation, investor interest, sector momentum, public-market conditions, expected timing of a liquidity event, and the availability of shares for sale. Demand can also be affected by transfer restrictions, company approval rights, right of first refusal processes, limited information, and the price expectations of buyers and sellers. Strong demand does not guarantee strong pricing, liquidity, or investment returns. Weak demand does not necessarily reflect the company's long-term prospects. Demand signals should not be treated as a recommendation or prediction of investment performance. Buyers and sellers should treat demand signals as informational and conduct their own diligence before transacting.
Sellers often rely on intermediaries and platforms, such as SetterVC and other secondary-market platforms, to identify potential buyers. The exact process varies by company and transaction, but sellers often begin by confirming their ownership, desired price, transferability, and any company approval or notice requirements. If the seller agrees with a buyer on acceptable price and terms, the company may need to be notified through a share transfer notice or similar process. If a right of first refusal, company approval right, or other transfer restriction applies, the seller may need to wait until that process is completed. The parties may then execute a purchase and sale agreement, complete required transfer documentation, and close if all required conditions are satisfied. Sellers should always seek proper legal and financial advice before completing the transaction.
Yes, current and former Kyoto Fusioneering employees, early investors, and other existing shareholders may be able to sell vested shares before an IPO through a private secondary sale. This is not automatic; it depends on whether the shareholder has transferable shares, whether there is buyer demand, and whether the company's governing documents permit the transfer. Many companies require prior notice, company approval, or a right of first refusal before shares can be sold. Sellers should also seek proper legal and financial advice before proceeding.
A Kyoto Fusioneering secondary transaction usually involves an existing shareholder selling shares to a buyer before a public listing. The buyer and seller typically agree on price, number of shares, share class, and closing conditions. The seller may then need to notify Kyoto Fusioneering through a share transfer notice or similar process. If Kyoto Fusioneering or existing investors have approval rights, transfer restrictions, or a right of first refusal, those steps may need to be completed before the transfer can close. The parties typically enter into a purchase and sale agreement, complete any required transfer documentation, and close only if the necessary conditions are satisfied. Timing and certainty can vary by company and transaction.
In most private secondary transactions, parties commonly use a purchase and sale agreement that outlines price, terms, and conditions. They may also use share transfer documentation, often a stock transfer notice, share transfer notice, transfer instruction, or similar document, along with any required company approval or right of first refusal materials. Proof of ownership, such as a cap table entry, share certificate, brokerage statement, issuer confirmation, or administrator confirmation, may also be important. Buyers often request recent company financials, but private companies may limit disclosure. Since every deal varies, buyers and sellers should consult legal and financial advisors to understand which documents are needed.
Buying Kyoto Fusioneering shares pre-IPO is risky. Shares are illiquid, no IPO or liquidity event is guaranteed, valuations can change, transfers may require company approval, and private companies may provide limited financial disclosure. Be prepared for total loss. SetterVC and Setter Capital do not provide due diligence, legal, tax, accounting, valuation, or investment advice. Buyers must conduct their own due diligence, verify information, and seek independent legal and investment advice before proceeding.
Private secondary shares are typically illiquid. Unlike public stocks, there is no active public market, so selling them can be difficult and time-consuming. Sales depend on finding a willing buyer and often require company approval. Investors should be prepared to hold the shares for an extended period, with no guarantee of a future sale. Always assess your need for liquidity before investing.
SetterVC and Setter Capital do not provide due diligence, legal, tax, accounting, valuation, or investment advice. Buyers must conduct their own due diligence, including verifying ownership, transferability, legal structure, company approval, and assessing the company's prospects. SetterVC and Setter Capital do not provide advice on whether an investment is good, what price to pay, or what the best bid or ask is. SetterVC and Setter Capital may share documents in some circumstances, but it does not guarantee their accuracy or completeness. Due diligence is essential. Seek legal and investment advice as needed.
Before buying Kyoto Fusioneering shares, a buyer should try to review the share class, price per share, implied valuation, transfer restrictions, ROFR process, company approval rights, seller ownership evidence, recent financing or tender-offer information, available financial information, information rights, resale restrictions, tax considerations, and expected liquidity paths. Not all information may be available for a private company. Buyers should confirm available diligence, process details, and information needs with their own legal, tax, and investment advisers.
SPVs carry risks. Examples include the need to confirm the company allows SPV-based transfers, verify that the SPV truly owns the shares or interests it claims to own, and ensure it has not sold more interests than it holds. Due diligence is essential. Seek legal and investment advice as needed.
Forward contracts carry risks. Examples include the seller refusing to transfer the shares at the future date, even if the seller owns them, the seller going bankrupt with creditors claiming the shares, or the seller committing the same shares to multiple parties. Due diligence is essential. Seek legal and investment advice as needed.
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