- 2013/04 - 2022/03 The Japan Society for Industrial and Applied Mathematics (JSIAM) Member delegate
- 2013/05 - 2014/06 The Japan Society for Industrial and Applied Mathematics (JSIAM) Vice President
- 2012/04 - 2014/06 The Japan Society for Industrial and Applied Mathematics (JSIAM) Member of the Board of Trustees
- 2008/05 - 2012/03 The Japan Society for Industrial and Applied Mathematics (JSIAM) Member of the editorial board of the JSIAM Letters
- 2006/05 - 2012/03 The Japan Society for Industrial and Applied Mathematics (JSIAM) Member of the steering committee for JSIAM FAIS (Special Interest Group on Formal Approach to Information Security)
- 2008/02 - 2011/03 Japan Science and Technology Agency (JST) Member of French-Japanese Collaboration Project on Computational Soundness (CNRS-JST)
- 2008/05 - 2009/05 The Institute of Electronics, Information and Communication Engineers (IEICE) Member of the editorial board of "Special Section on Formal Approach"
- 2009/04 - 2009/04 CoSyProofs 2009 (Spring School and Workshop on Computational and Symbolic Proofs of Security) Member of the organizing committee
- 2001/04 - 2009/03 Japan Society for Software Science and Technology (JSSST) Member of the editorial board of the JSSST Computer Software Journal
- 2008/10 - 2008/10 The Institute of Electronics, Information and Communication Engineers (IEICE) Member of the writing committee for the IEICE Knowledge-Base
- 2008/05 - 2008/05 Information Processing Society of Japan (IPSJ) Guest editor of the special features on "New Trends in Formal Methods," IPSJ Magazine
- 2001/04 - 2005/03 Information Processing Society of Japan (IPSJ) Member of the steering committee for IPSJ SIGAL (Special Interest Group on Algorithms)
- 1996/06 - 2000/03 Information Processing Society of Japan (IPSJ) Editor of the IPSJ Magazine
- PASSAT (IEEE/ASE International Conference on Privacy, Security, Risk, and Trust) 2010, 2011, 2012, 2013 Member of the program committee
- DPM (International Workshop on Data Privacy Management) 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021 Member of the program committee
- ICISSP (International Conference on Information Systems Security and Privacy) 2015, 2016, 2017, 2018, 2019, 2020 Member of the program committee