Apr 1965 Joined Fujii Accounting Office Aug 1970 Established Osaka Sanai Co., Ltd. (now OSG Corporation); assumed office as Representative Director, President Apr 1987 Acquired Shin Daiwa Department Store Co., Ltd. (now Sanai Cosmos Co., Ltd.); assumed office as Representative Director, President of the same company (current) Apr 1990 Established G.A.T. Research Institute Co., Ltd.; assumed office as Representative Director, President of the same company (current) May 2004 Established Tiannian Sanai Environmental Technology (Suzhou) Co., Ltd. (now Oai Water (Shanghai) Environmental Technology Co., Ltd.); assumed office as Chairman of the same company Feb 2006 Assumed office as Representative Director, Chairman of Nichiden Co., Ltd. (now OSG Watertech Co., Ltd.) Oct 2006 Assumed office as Representative Director, President of Water Net Co., Ltd. Apr 2007 Assumed office as Representative Director, Chairman and CEO of OSG Corporation (current) Sep 2010 Assumed office as Chairman of Zhuhai Oai Water Foundation Technology Co., Ltd. (now Shanghai Oai Environmental Technology Co., Ltd.) Mar 2013 Assumed office as Representative Director, Chairman of Water Net Co., Ltd. Apr 2020 Assumed office as Representative Director, Chairman of Ginza Nishikawa Co., Ltd. (current)

Apr 1994 Joined OSG Corporation (now the Company) Aug 2003 Assumed office as General Manager of Sales Department, OSG Corporation Feb 2011 Assumed office as General Manager of Sales Headquarters for Western Japan, OSG Corporation Mar 2013 Assumed office as Representative Director, President of Water Net Co., Ltd. Apr 2013 Assumed office as Director, OSG Corporation Apr 2021 Assumed office as Representative Director, President, OSG Corporation (current) Apr 2023 Assumed office as Director of Ginza Nishikawa Co., Ltd. (current)

Apr 1986 Joined Osaka Sanai Co., Ltd. (now OSG Corporation) Feb 1998 Assumed office as Director, General Manager of Business Division, OSG Corporation Jan 2000 Assumed office as Director of G.A.T. Research Institute Co., Ltd. (current) Apr 2007 Assumed office as Representative Director, President, OSG Corporation Sep 2007 Assumed office as Director of Water Net Co., Ltd. Feb 2009 Assumed office as Representative Director, President of Nichiden Co., Ltd. (now OSG Watertech Co., Ltd.) Mar 2016 Assumed office as Director of OSG Watertech Co., Ltd. Apr 2017 Assumed office as Representative Director, President of OSG Communications Co., Ltd. Sep 2017 Assumed office as Chairman of Oai Water Foundation Environmental Technology (Suzhou) Co., Ltd. (now Oai Water (Shanghai) Environmental Technology Co., Ltd.) (current) Mar 2021 Assumed office as Representative Director, President of OSG Watertech Co., Ltd. (current) Apr 2021 Assumed office as Vice Chairman of OSG Corporation Apr 2022 Director of Ginza Nishikawa Co., Ltd. Apr 2023 Assumed office as Director, OSG Corporation Apr 2026 Assumed office as Director, General Manager of Administration Division, OSG Corporation (current)

Apr 1994 Joined OSG Corporation (now the Company) Aug 2003 Assumed office as General Manager of Sales Department, OSG Corporation Feb 2011 Assumed office as General Manager of Sales Headquarters for Eastern Japan, OSG Corporation Mar 2013 Assumed office as General Manager of Sales Headquarters, OSG Corporation Apr 2013 Assumed office as Director, OSG Corporation Aug 2015 Assumed office as General Manager of Business Division, OSG Corporation Apr 2019 Assumed office as Director of OSG Communications Co., Ltd. Feb 2021 Assumed office as General Manager of Sales Headquarters, OSG Corporation (current) Mar 2021 Assumed office as Director of OSG Watertech Co., Ltd. (current) Apr 2021 Assumed office as Director, OSG Corporation (current)

Apr 1987 Joined Osaka Sanai Co., Ltd. (now OSG Corporation) Apr 2012 Assumed office as Audit & Supervisory Board Member of OSG Communications Co., Ltd. Apr 2013 Assumed office as General Manager of Operations Department, OSG Corporation Feb 2015 Assumed office as General Manager of Accounting Department, OSG Corporation Aug 2016 Assumed office as General Manager of Finance Department, OSG Corporation Apr 2020 Assumed office as Director, General Manager of Administration Department, OSG Corporation (current) Apr 2021 Assumed office as Audit & Supervisory Board Member of Water Net Co., Ltd. (current) Apr 2023 Assumed office as Audit & Supervisory Board Member of OSG Watertech Co., Ltd. (current)

Apr 1974 Joined Mitsubishi Metal Corporation (now Mitsubishi Materials Corporation) Feb 2000 Joined Nichiden Co., Ltd. (now OSG Watertech Co., Ltd.) Feb 2012 Assumed office as Director of OSG Watertech Co., Ltd. Mar 2016 Assumed office as Representative Director, President of OSG Watertech Co., Ltd. Apr 2020 Assumed office as Director, OSG Corporation May 2021 Assumed office as Director of Ginza Nishikawa Co., Ltd. Apr 2023 Assumed office as Director (Audit and Supervisory Committee Member, Full-time), OSG Corporation (current)

Mar 2007 Joined Deloitte Touche Tohmatsu (now Deloitte Touche Tohmatsu LLC) Oct 2010 Registered as Certified Public Accountant Jul 2017 Joined Yusei Audit Corporation (now Taiyo LLC Audit Corporation) Sep 2018 Opened Katsutaka Yamaguchi CPA Office Oct 2018 Assumed office as Representative Director, Teleoaffect FAS Co., Ltd. (current) Apr 2021 Assumed office as Director, Audit and Supervisory Committee Member, OSG Corporation (current) Nov 2021 Assumed office as Outside Director, WOLVES HAND Co., Ltd. (current)

Sep 2008 Completed training at the Legal Training and Research Institute of the Supreme Court; joined Taiyo Law Office; registered as Attorney at Law (Osaka Bar Association) Apr 2017 Assumed office as Co-Managing Partner, Taiyo Law Office (current) Apr 2021 Assumed office as Director, Audit and Supervisory Committee Member, OSG Corporation (current)