Pursuing a dream of becoming an automobile designer, Nakaima sat for an exam to apply for the Government-funded/Self-funded Okinawa Student Program, a system established between the United States Military Government in Okinawa and the Japanese Government to allow students from Okinawa to attend university in mainland Japan. Nakaima passed the exam and matriculated at the University of Tokyo, where he graduated with a Bachelor of Engineering degree in 1961.
Directly after graduating in 1961, Nakaima joined the Ministry of International Trade and Industry (MITI). In the 1980s, Nakaima served as the Director General of the Commerce and Industry Department at the Okinawa General Bureau and later as the Deputy Director-General for Technology Affairs at MITI's Agency of Industrial Science and Technology.
In 1987, Nakaima took a Senior General Manager position with the Okinawa Electric Power Company. In 1990, he left the company to become a Vice Governor in the administration of Okinawa Governor Masahide Ota. Nakaima returned to the Okinawa Electric Power Company in 1995, serving as the company's President and later Chairman of the Board of Directors.
In 2006 the Liberal Democratic Party and the Fair and Clean Government Party gave him backing for his run in the Okinawa gubernatorial election on November 19. In the election, Nakaima defeated Itokazu Keiko, who received the recommendation of five opposition parties. Nakaima assumed the office of Governor on December 10, 2006.