大学卒業後、ベイン・アンド・カンパニーに入社し、消費財、金融機関、流通業などを中心に日本への参入戦略や新規事業戦略を担当。大学院卒業後、GE、Johnson & Johnsonなど複数の企業にて業務変革などに従事。
「人々の健康、医療格差の是正」への関心が高く、製薬・医療機器など医療業界に20年以上身を置いている。2000年にGE Plastics Japan (現Sabic)　代表取締役CFO就任、その後、複数社の社長を歴任し、2024年PHCホールディングス株式会社　代表取締役社長CEOに就任。現職。

Kyoko (Kay) Deguchi began her career at Bain and Company in 1989. In 1997, she joined The Disney Store Japan to lead new business development. In 2000, she became the CFO and the first female board member at GE Plastics Japan.

Kay's career in healthcare expanded at Janssen Pharmaceuticals, where she worked in the US, Australia, and Japan, overseeing Alzheimer's disease, GERD, and establishing the Japan oncology franchise. She later served as President of Stryker Japan and then as Vice President and General Manager for Japan at AbbVie GK Japan, leading cultural transformation and process optimization.

In 2014, Kay joined Ochanomizu Orthopedic Rehab Clinic as Vice Director. In 2022, she co-founded a new orthopedic clinic in Niigata Prefecture to address the medical needs of the growing elderly population in rural areas. In 2024, Kay became President and Representative Director at PHC Holdings, Inc., where she currently serves.

Kay is also a professor at Kenichi Ohmae Graduate School of Business, where she teaches Corporate Finance. Additionally, she serves as an independent director for Heartseed, a leading company in regenerative medicine.

Kay holds a BA in Law from Tokyo University and graduated with distinction from Harvard Business School.