Tamio Umaki joined ORIX in 1972. After a number of positions in the company, he was appointed Secretary to the President, Office of the President in February 1996 and then General Manager, Business Planning & Development Department in October of the same year, with responsibility of the Sales Promotion Department added in 1997. He became a Corporate Executive Officer and Deputy Head of the District Sales Headquarters from 1999, and was appointed Deputy Head of the Tokyo Sales Headquarters in November 2000 before assuming the position as President of ORIX Rentec Corporation in January 2002. Umaki became a Group Executive under a "Company with Committees" structure in June 2003 and was promoted to the position of Group Senior Vice President in January 2007. In October 2008 Umaki was appointed Corporate Senior Vice President, CIO, and added the IT Planning Office to his duties. Umaki was given the duties of overseeing the Human Resources and Corporate Administration Headquarters in January 2009, and the additional duties of overseeing the Administration Center and Asset Administration Department in March 2009.

Umaki was born in 1948.