Takuma Takeuchi

My research interests include blockchain security, blockchain interoperability, and related issues. Currently, I am approaching these issues with research and open source development activities.

Research interests

Blockchain technology, including blockchain security and blockchain interoperability
Distributed systems, including distributed AI and data trust
Rubik’s Cube

Curriculum vitae

Work experience

Apr.2013–now: Fujitsu Limited
- Apr.2023–now: Senior Research Manager, Fujitsu Research, Fujitsu Limited
- Apr.2022–Mar.2023: Research Manager, Fujitsu Research, Fujitsu Limited
- Oct.2021–Mar.2022: Senior Researcher, Fujitsu Research, Fujitsu Limited
- Apr.2021–Sep.2021: Researcher, Fujitsu Research, Fujitsu Limited
- Apr.2013–Mar.2021: Researcher, Fujitsu Laboratories Ltd.
May.2020–now: Linux Foundation Decentralized Trust / Hyperledger Foundation
- Nov.2025–now: Emeritus Maintainer, Hyperledger Cacti, Linux Foundation Decentralized Trust
- Sep.2024–Oct.2025: Maintainer, Hyperledger Cacti, Linux Foundation Decentralized Trust
- Sep.2022–Aug.2024: Maintainer, Hyperledger Cacti, Hyperledger Foundation
- May.2020–Aug.2022: Maintainer, Hyperledger Cactus, Hyperledger Foundation
Apr.2023–Mar.2024: Fujitsu Research of Europe Ltd.
- Apr.2023–Mar.2024: Senior Research Manager, Fujitsu Research of Europe Ltd.
Jan.2022–Mar.2023: Fujitsu Research of America, Inc.
- Apr.2022–Mar.2023: Research Manager, Fujitsu Research of America, Inc.
- Jan.2022–Mar.2022: Member of Research Staff, Fujitsu Research of America, Inc.
Sep.2010–Mar.2011: Bioinformatics Institute for Global Good, Inc.
- Sep.2010–Mar.2011: Part-time Software Developer, Bioinformatics Institute for Global Good, Inc.

Education

Apr.2026–now: Doctoral student, University of Tsukuba
- Apr.2026–now: Doctoral Program in Risk and Resilience Engineering, Degree Programs in Systems and Information Engineering, Graduate School of Science and Technology, University of Tsukuba
Apr.2011–Mar.2013: Master’s degree of Informatics, Kyoto University
- Apr.2011–Mar.2013: Department of Applied Mathematics and Physics, Graduate School of Informatics, Kyoto University
Apr.2007–Mar.2011: Bachelor’s degree of Engineering, The University of Tokyo
- Apr.2009–Mar.2011: Department of Mathematical Engineering and Information Physics, Faculty of Engineering, The University of Tokyo
- Apr.2007–Mar.2009: Division of Natural Sciences 1, College of Arts and Sciences, The University of Tokyo

Research and development activities

Referred journals and conference proceedings

Florian Zimmer, Janosch Haber, Mayuko Kaneko, Takuma Takeuchi, “Towards a Levels of Assurance for Data Trustworthiness Framework: A Design Science Approach” (journal), Communications in Computer and Information Science, to be published, 2026.
Shingo Fujimoto, Takuma Takeuchi, Yoshiki Higashikado, “Secure Blockchain Interworking Using Extended Smart Contract” (journal), IEICE TRANSACTIONS on Information and Systems, vol. E105-D, no. 2, pp. 227–234, Feb. 2022, doi: 10.1587/transinf.2021BCP0002.
Shingo Fujimoto, Yoshiki Higashikado, Takuma Takeuchi. “ConnectionChain: Secure Interworking of Blockchains” (proceeding), Proc. 2019 Sixth Int. Conf. on Internet of Things: Systems, Management and Security (IOTSMS). Granada, Spain, 2019, pp. 514–518, doi: 10.1109/IOTSMS48152.2019.8939267.
Takuma Takeuchi, Toshiya Shimizu, Ken Kamakura, Takeshi Shimoyama, Hiroshi Tsuda. “A Limited-Use Asset Management System on the Blockchain Platform with an Extended Open Assets Protocol” (proceeding), Proc. 23rd Annual Int. Conf. on Advanced Computing and Communications (ADCOM 2017), Kerala, India, 2017, pp. 1-7, doi: 10.1109/ADCOM.2017.8691930.

Non-referred presentations

Florian Zimmer, Janosch Haber, Mayuko Kaneko, Takuma Takeuchi: “Towards Levels of Assurance for Data Trustworthiness - A Novel Framework to Promote Trust in Inter-Organisational Data Sharing” (workshop paper), 18th Workshop on Social and Human Aspects of Business Process Management (BPMS2 2025), 19th International Conference on Research Challenges in Information Science (RCIS2025), Spain, 2025.
Takuma Takeuchi, Peter Somogyvari, Tracy Kuhrt, Venkatraman Ramakrishna, Susumu Toriumi: “Panel Discussion: Blockchain Interoperability with Hyperledger Cactus, Weaver, and YUI” (presentation), Hyperledger Global Forum 2022 (HGF2022), Ireland, 2022. [Youtube]
Jim Zhang, Sophia Lopez, Peter Somogyvari, Venkatraman Ramakrishna, Takuma Takeuchi: “Panel Discussion: All Things Cross-Chain” (presentation), Hyperledger Global Forum 2022 (HGF2022), Ireland, 2022. [Youtube]
Takuma Takeuchi. “A blockchain interoperability solution for creating token economies - Hyperledger Cactus” (presentation), DeveloperWeek2022, Virtual and USA, 2022.
Takuma Takeuchi, Yoshiki Higashikado, Shingo Fujimoto. “A secure cross-chain platform for business blockchain applications” (poster), The 14th International Workshop on Security (IWSEC2019), Japan, 2019.
Takuma Takeuchi, Hiroto Sekido. “An approximate approach to E-optimal designs for weighted polynomial regression by using Tchebycheff systems and orthogonal polynomials” (poster), China-Japan Joint Workshop on Integrable Systems 2013, Japan, 2013.
Takuma Takeuchi, Hiroto Sekido. “On the E-optimal design of weighted polynomial regression using the Tchebycheff system and orthogonal polynomials” (poster), The 7th JSS Spring Meeting (The Japan Statistics Society), Japan, 2013.
Takuma Takeuchi, Ryuta Hashimoto, Daishi Aiura, Yin Xin, Takuya Kato, Kazuma Tsukamoto, Takeru Matsuda. “5x5x5 Rubik’s Cube Solver and its subprogram with GAP” (presentation), Risa/Asir Conference 2012, Japan, 2012.
Fuyuhiko Tanaka, Takuma Takeuchi. “Hypothesis testing of a maximally entangled state under the unknown unitary process” (poster), Quantum Information Processing 2012 (QIP2012), Canada, 2011.
Takuma Takeuchi, Fuyuhiko Tanaka. “Hypothesis Testing of Quantum State Models with Disturbing Parameters” (presentation), Japan Federation of Statistical Science Associations, Japan, 2011.

Invited presentations

Takuma Takeuchi. “Learning and security technologies toward trustworthy decentralized and collaborative AI” (presentation), IEICE General Conference, Japan, 2026. [Proceeding(Japanese)]
Takuma Takeuchi. “An introduction to research activities of security and blockchain on Fujitsu” (presentation), Human Network for Researchers toward Advanced Telecommunications (AC Net), Online, 2021.
Takuma Takeuchi. “The overview of Hyperledger Cactus V0.4 and its plan for future development” (presentation), Hyperledger Tokyo Meetup, Online, 2021. [Slideshare(Japanese)], [Youtube(Japanese)]
Takuma Takeuchi. “An introduction to the new project, Hyperledger Cactus” (presentation), Hyperledger Tokyo Meetup, Online, 2020. [Slideshare(Japanese)], [Youtube(Japanese)]

Technical articles

Hirokazu Anai, Katsuki Fujisawa, et al. (including Takuma Takeuchi): “Realizing Socially Acceptable Sustainable Engineering through Generative AI” (technical report), Council on Competitiveness-Nippon (COCN), 2025. [Report(Japanese)]
Peter Somogyvari, Jagpreet Singh Sasan, Izuru Sato, Takuma Takeuchi, Venkatraman Ramakrishna, Sandeep Nishad, Krishnasuri Narayanam, Dhinakaran Vinayagamurthy: “Introducing Hyperledger Cacti, a multi-faceted pluggable interoperability framework” (technical blog), Hyperledger Blog, 2022. [Blog]
Peter Somogyvari, Takuma Takeuchi. “Hyperledger Cactus: Release V1 on the Road to General Blockchain Integration” (technical blog), Hyperledger Blog, 2022. [Blog]

Interview articles

Takuma Takeuchi. “Thinking outside of the box – focusing on boundaries between multiple heterogeneous technologies to build new attractive technology” (interview blog), Researcher’s Dream, Fujitsu Research, 2022. [Blog]

Open source software development

Hyperledger Cacti (Cactus) - Emeritus Maintainer (2025–now), Maintainer (2020–2025)

Awards

Best Idea and Use Case Award, Smart Contract Japan 2016 Blockchain Hackathon, 2016.
Best Student Presentation Award, The 7th JSS Spring Meeting (Japan Statistical Society), 2013.

Remark

The views expressed here are my own and do not represent my organization.