Okada was born in Mito, Ibaraki, near the main factory of Hitachi, which was founded by his grandfather Namihei Odaira.
His father, Tsuneyoshi Okada [ja], was a senior bureaucrat at the Home Ministry who served as Governor of Tokushima and Hokkaido.
[1][2][3] Following in his father and grandfather's footsteps, he attended the University of Tokyo, graduating in 1955.
He stayed at the university for two extra years after that to do his master's degree in architecture.
[5] His other notable works include the Metropolitan Police Headquarters, Okayama Orient Museum, the University of Tokyo Hospital's high-rise complex, and Miyazaki Prefectural Art Museum.