Series C Extension reaches its final close, positioning KF for the next phase of growth
Kyoto Fusioneering (KF), a Japanese deep-tech startup pioneering the engineering of fusion energy power plants, today announced the successful completion of new funding totaling ¥9.3 billion through equity and debt financing.
This latest round includes ¥1.45 billion in equity financing, with participation from four new investors, notably Kyocera Venture Innovation Fund-I (KVIF-I Limited Partnership, General Partner: Global Brain Corporation), JERA Co, Inc, and Sumitomo Mitsui Trust Bank, Limited.
In addition, KF finalized its Series C extension round, led by 31VENTURES – Global Brain – Growth I GK jointly managed by Mitsui Fudosan Co., Ltd. and Global Brain Corporation, bringing the cumulative total raised in Series C Extension (including two previously announced rounds*1) to ¥4.0 billion.
To further strengthen its capital base, KF also secured ¥5.3 billion in debt financing and credit facilities from Japan Finance Corporation, Japan Bank for International Cooperation (JBIC), MUFG Bank, Ltd, Sumitomo Mitsui Banking Corporation, and The Bank of Kyoto, Ltd.
As a result, Kyoto Fusioneering has now raised a combined ¥9.4 billion in this extension round and financing package, bringing its total cumulative equity financing to ¥16.2 billion.
1. Global Strategic Developments in Fusion Energy
On the international stage, the United States, the United Kingdom, and China are accelerating their own efforts to demonstrate fusion-based power generation in the 2030s and 2040s. Among them, China stands out for its rapid progress, driven by strong government leadership and investment, making it a closely watched player in the race toward commercial fusion energy.
2. Strategic Developments in Japan’s Fusion Energy Sector
Momentum toward commercial fusion power as a reality is accelerating in Japan. The Fusion Energy Innovation Strategy, first introduced in April 2023 as a national policy, was revised in June 2025. The updated strategy now sets a clear national goal: to demonstrate fusion-based power generation in the 2030s.
In line with this vision, Kyoto Fusioneering launched the FAST (Fusion by Advanced Superconducting Tokamak) project in November 2024, taking on the role of project leader. FAST represents a private-sector-driven, industry–academia collaboration with the ambitious aim of proving fusion electricity generation within the 2030s in Japan. The initiative brings together leading researchers and companies, both in Japan and worldwide, to tackle the critical engineering challenges of fusion and to accelerate the transition from experimental reactors to practical, commercial-scale energy systems.
3. Kyoto Fusioneering’s Initiatives
Kyoto Fusioneering is entering a new business phase—one that builds on past technological breakthroughs while accelerating the integration of its systems to move closer to demonstration testing and, ultimately, the social implementation of fusion energy.
UNITY-1: At the core of this effort is the “UNITY-1” project, which aims to demonstrate how a fusion heat cycle system harnesses and utilises energy produced by fusion reactions. UNITY-1 has now reached the final stage of validating its power generation technology through a liquid metal loop. The project is on track to achieve a world first: successfully demonstrating power generation technology using a simulated fusion plant*2.
UNITY-2: In addition, the fusion fuel cycle system, which continuously supplies fuel, is undergoing performance testing of individual devices and systems at the company’s new R&D facility, established adjacent to its headquarters in January this year. In 2026, Fusion Fuel Cycles Inc., a joint venture between Kyoto Fusioneering and Canadian Nuclear Laboratories, will begin the world’s only integrated demonstration of a fuel cycle system in Canada, under the project “UNITY-2.”
FAST Project: In November last year, the “FAST” project—a privately led initiative to demonstrate fusion-based power generation, with Kyoto Fusioneering as a key participant—was officially launched. FAST’s mission is to prove that a complete fusion power generation system is possible by integrating plasma generation and control through D-T*3 fusion reactions, energy conversion, and fuel systems. Its goal is to validate power generation while addressing the key technical challenges that lie between today’s research and tomorrow’s commercialisation.
Currently, Starlight Engine Ltd. is leading the project, advancing conceptual design and site selection. The company has also begun joint research with leading domestic universities, building strong industry–academia partnerships to achieve power generation in the 2030s and pave the way for practical implementation of fusion energy.
FAST represents a major leap forward from Kyoto Fusioneering’s subsystem R&D to date—serving as a comprehensive test facility for full-scale fusion plants. With a scale expected to be nearly ten times larger than previous efforts, FAST marks a bold step toward turning fusion into a practical energy source for society.
Gyrotron Systems: Kyoto Fusioneering’s plasma heating system—the gyrotron system—has recently been adopted by Tokamak Energy Ltd. in the UK*4, further expanding its footprint in global fusion initiatives. To date, the company’s systems have been integrated into public fusion projects in the United States, United Kingdom, Germany and the Czech Republic. In a world-first demonstration, Kyoto Fusioneering successfully generated five distinct electromagnetic wave frequencies from a single gyrotron, driving forward both its business expansion and technological advancement in tandem*5. Looking ahead, the company continues to deepen partnerships with research institutions and private enterprises worldwide, strengthening its global presence and accelerating the realization of fusion energy.
4. Fundraising Overview
| Equity Financing | Debt Financing | |
| Amount | 1.45 Billion Yen Series C ・Extension Round Total: 4.0 billion Yen ・Cumulative total: 16.2 billion Yen | 5.3 Billion Yen (including credit facilities) |
| Investors / Lenders | ・Kyocera Venture Innovation Fund-I (KVIF-I Limited Partnership, General Partner: Global Brain Corporation) ・JERA Co., Inc. ・Sumitomo Mitsui Trust Bank, Limited ・One additional investor (undisclosed) Note: in alphabetical order | ・Japan Finance Corporation ・Japan Bank for International Cooperation (JBIC) ・MUFG Bank, Ltd. ・Sumitomo Mitsui Banking Corporation ・The Bank of Kyoto, Ltd. |
| Purpose of the Funding | ・Acceleration and scaling of technology development, including UNITY-1 and UNITY-2 ・Advancement of the FAST project ・Expansion of global operations and recruitment ・Working capital for large-scale project execution and business growth | ・Capital investment and working capital ・Financing for Fusion Fuel Cycles Inc. |
5. Comments from Satoshi Konishi, Co-Founder and CEO of Kyoto Fusioneering
We extend our sincere gratitude to the new investors and partners who have chosen to support our mission of realizing fusion energy at an early stage. As global fusion development gains momentum—and with Japan’s national strategy now setting a clear goal of demonstrating fusion power generation in the 2030s—we are entering a pivotal phase.
To succeed, we must fully leverage our expertise and network to accelerate progress toward the realization of fusion energy. On the technological side, our focus will be on the integration testing of systems essential for fusion power plants. On the business side, we will continue to act as one team, strengthening our global presence and contributing as a trusted partner to research institutions and private companies worldwide.
At the same time, we recognize that the scale of this challenge is greater than any single private startup can overcome alone. That is why we place great value on the knowledge and networks of our investors, which will help us meet each milestone—step by step—while maintaining the pace necessary to drive fusion development forward.
6. Equity Financing: Comments from Investors (in alphabetical order)
Mr. Shouichi Nakagawa
Executive Officer, Senior General Manager of Corporate R&D Group, KYOCERA Corporation
The realization of fusion energy is an effective method of sustainable energy to solve social issues such as global warming. I also believe that it will greatly contribute to the progress and development of human society. Kyoto Fusioneering’s technology is indispensable for converting fusion energy into usable energy. In order to contribute to this realization, Kyocera Venture Innovation Fund-I invested to Kyoto Fusioneering.
To make the dream come true, Kyocera will contribute with material technology and strengthen our relationship.
Mr. Takeshi Kodama
Head of JERA Ventures and Managing Partner, JERA Co., Inc.
JERA is exploring next-generation decarbonization technologies through JERA Ventures, our corporate venture capital arm, with the aim of achieving “JERA Zero CO2 Emissions 2050” We consider fusion energy one of the most promising energy sources for the future because it does not emit CO₂ and is an inexhaustible source of energy. We share Kyoto Fusioneering’s vision of commercializing fusion energy. With this investment as a starting point, we will engage in concrete discussions on collaboration toward the social implementation of fusion power generation and work together to realize a stable energy supply and a decarbonized society.
Mr. Takehiko Sakaue
Managing Executive Officer, Sumitomo Mitsui Trust Bank, Limited
We are profoundly inspired by Kyoto Fusioneering’s bold pursuit of “industrializing nuclear fusion” and the grand ambition of transforming Japan into an energy-exporting nation. Their steadfast commitment to realizing “the ultimate clean energy” is truly admirable. By uniting world-class technological expertise with Japan’s renowned manufacturing excellence, Kyoto Fusioneering is working to deliver the future of power generation infrastructure to the world. Their vision and determination represent as beacon of hope and pride for Japan.
We strongly believe that the passion and technological strength of the Kyoto Fusioneering team will open the door to a brighter future. At Sumitomo Mitsui Trust Bank, we are wholeheartedly committed to supporting their journey every step of the way.
7. Debt Financing: Comments from Lenders
Mr. Koichiro Asai
Branch Manager, Small and Medium Enterprise Unit, Kyoto Branch, Japan Finance Corporation (JFC)
Kyoto Fusioneering has established an extremely important position in the industry in terms of its technological capabilities and management strategy, and there are high expectations for the company as a company that will be responsible for building a domestic supply chain and creating a major industry with a market size expected to be several tens of trillions of yen. We hope that the “Startup Support Loan” that we have provided will be put to good use in the commercialization of fusion energy, which holds the key to opening up a sustainable and clean future.
Mr. Tomohiko Maruyama
Managing Officer for Osaka, Industry Finance Group, Japan Bank for International Cooperation (JBIC)
Japan Bank for International Cooperation is pleased to provide debt finance in support of the construction and operation of “UNITY-2,” an integrated demonstration facility for fusion fuel cycles, to be developed by Fusion Fuel Cycles Inc., the Canadian group company of Kyoto Fusioneering Ltd.
The government of Japan has positioned fusion energy as a next-generation energy source in its key policy initiatives such as the Fusion Energy Innovation Strategy and the Seventh Strategic Energy Plan and is committed to strengthening public-private R&D capabilities, including support for startups. In that context, UNITY-2 plays a vital role that contributes to enhancing Japan’s fusion-related R&D.
We hope our financial support will help accelerate R&D of fusion fuel cycle systems and contribute to the realization of fusion energy. We also look forward to seeing Kyoto Fusioneering, a leading Japanese fusion startup, further expand its presence and impact globally.
Mr. Yuji Kosugi
Executive Officer, General Manager of Kyoto Branch, MUFG Bank, Ltd.
Kyoto Fusioneering is a globally leading startup driving the early industrialization of fusion energy.
This financing will support the the demonstration of plant technologies at UNITY-2, contributing to the establishment of safe tritium handling practices in fusion power plants and accelerating the realization of fusion energy.
At MUFG, we have identified “achieving a carbon-neutral society” and “supporting industrial development and innovation” as priority initiatives. As part of the MUFG Group, we remain committed to supporting Kyoto Fusioneering’s continued growth in alignment with these goals.
Mr. Hiroaki Yoshikawa
General Manager, Growth Business Development Dept., SUMITOMO MITSUI BANKING CORPORATION
Fusion energy is expected to serve as a next-generation clean energy source that places minimal burden on the global environment and contributes to the realization of a carbon-neutral society. The grand challenge of industrializing fusion energy is an important undertaking for Japan.
SMBC Group positions efforts for Social Value Creation as one of the pillars of our management philosophy and is dedicated to fostering industries that contribute to such value creation. Through continued support for a wide range of companies, we remain committed to driving innovation that addresses social issues.
Mr. Kazuhiko Iwata
HEAD OFFICE DEPUTY GENERAL MANAGER, THE BANK OF KYOTO LTD.
Kyoto Fusioneering is taking on the challenge of cutting-edge fusion energy technologies and playing a vital role in realizing the “dream energy.” As a startup originating from Kyoto, the company continues to develop its technologies in Kyoto and other locations. We hold high expectations for the company’s technology and, in support of its further growth, have decided to provide financing. As a company with deep ties to Kyoto, we are committed to walking alongside Kyoto Fusioneering and supporting its sustainable growth into the future.
8. Current Investors (in alphabetical order)
- 31VENTURES – Global Brain – Growth I GK (General Partners: Mitsui Fudosan Co., Ltd. and Global Brain Corporation)
- Coral Capital
- Daiwa Corporate Investment Co., Ltd.
- DBJ Capital Co., Ltd.
- Electric Power Development Co.,Ltd. (J-POWER）
- Fujikura Ltd.
- INPEX CORPORATION
- In-Q-Tel（IQT）
- JAFCO Group Co., Ltd.
- JAPAN CO-INVEST IV LIMITED PARTNERSHIP / SUMITOMO MITSUI TRUST INVESTMENT CO., LTD.
- JGC MIRAI Innovation Fund L.P. (General Partner: Global Brain Corporation)
- JIC Venture Growth Investments Co., Ltd
- K4 Ventures GK (Kansai Electric Power Group）
- Kyogin Shining Future Support Fund III for SDGs Investment Limited Partnership General Partner: Kyoto Capital Partners Co., Ltd. (KCAP)
- Kyoto University Innovation Capital Co., Ltd.
- Marubeni Corporation
- Mitsubishi Corporation
- Mitsubishi UFJ Capital Co., Ltd.
- MITSUI & CO., LTD.
- Mitsui Fudosan Co., Ltd.
- MOL PLUS Co., Ltd.
- MUFG Bank, Ltd.
- NICHICON CORPORATION
- SMBC VENTURE CAPITAL CO., LTD.
9. Kyoto Fusioneering
Founded in 2019, Kyoto Fusioneering is a privately funded deep-tech startup with offices and facilities in Tokyo and Kyoto (Japan), Culham (UK), Seattle (US), and Karlsruhe (Germany). The company specialises in developing the critical technologies needed for commercial fusion power plants, including gyrotron systems, tritium fuel cycle solutions, and breeding blankets for tritium production and power generation.
Working hand-in-hand with public and private fusion developers worldwide, Kyoto Fusioneering’s mission is to make fusion energy the ultimate sustainable solution to humanity’s energy needs.
Learn more about our vision for the future of energy at www.kyotofusioneering.com/en/ or contact us at media@kyotofusioneering.com.
Note
*1: Kyoto Fusioneering Raises 1.5 Billion Yen in Series C Extension Round / Kyoto Fusioneering Closes 2nd Round of 1.1 Billion Yen Series C Extension Led by In-Q-Tel (IQT), Marubeni and Nichicon
*2: The UNITY-1 test does not initiate fusion reactions and does not involve the handling of any radioactive materials.
*3: Refers to a fusion reaction using deuterium and tritium.
*4: Kyoto Fusioneering’s Advanced Gyrotron Technology to Support Fusion Experiments on Tokamak Energy’s World-Leading ST40 Facility
*5: A World First: A Single Gyrotron produces five separate frequencies of electromagnetic beam output
