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Ryo Okazaki was born on October 6, 1960, and passed away on August 5, 2018, due to a sudden water accident during his summer vacation with his family. Our first encounter goes back to 34 years ago, when he graduated from the University of Tokyo Medical School and started his residency at the University Hospital in 1985. He was a motivated and enthusiastic young physician with great interest in endocrine disorders. I recruited him to our group, and soon after he finished his residency, he joined our laboratory at the Fourth Department of Internal Medicine, University of Tokyo.

He was a passionate and dedicated physician, and was devoted to taking care of patients with difficult problems. While he saw patients with younger fellows and residents and taught them in the hospital ward, he started his research works on bone biology in our laboratory. To deepen his bone research, he became a postdoctoral fellow, supervised by Professor Lawrence Riggs at the Endocrine Research Unit of Mayo Clinic from September, 1991, until the end of 1994. After coming back to Tokyo in 1995, he worked at the Division of Endocrinology and Metabolism, Kanto Teishin Hospital, where he extended his expertise to diabetes, and published a well-known clinical study on the change in bone turnover markers in poorly controlled type 2 diabetic patients during rapid control of glucose metabolism.

In 1999, Ryo Okazaki was offered a staff position in the 3rd Department of Internal Medicine, Teikyo University. Ryo accepted to move to Teikyo University in Chiba as an Assistant Professor in April, 1999. He did a great job there to be promoted to an Associate Professor in 2004 and became a full Professor in 2007 under the new name of the institute, Teikyo University Chiba Medical Center. After that, he started many clinical studies in Chiba area, including studies demonstrating the importance of chronic obstructive pulmonary disease as a major cause for secondary osteoporosis in males.

He played an important role in the development of diagnostic criteria for rickets and osteomalacia in 2015, and a key role in the development and implementation of assessment criteria for vitamin D deficiency/insufficiency in Japan in 2017 as a member of the expert panel sponsored by the Ministry of Health, Labor and Welfare of Japan, the Japanese Society for Bone and Mineral Research, and the Japan Endocrine Society. These criteria played an essential role for the approval of serum 25-hydroxyvitamin D measurement for rickets/osteomalacia and for osteoporosis in Japan.

He was recently elected as a Board Member of the Japan Osteoporosis Society and was expected to be among the next leaders in the field of bone and mineral research in Japan. Ryo was wonderful to work with, transmitting excitement and energy. Ryo was a man of great intellect and scholarship, and was loved by many friends and colleagues. He loved his wife Asami and is survived by Asami and their son Haru, to whom we convey the deepest sympathy from Ryo’s many colleagues and friends.