[4] After the fall of the shogunate, the Owadas participated in a salmon-fishing cooperative,[3] the proceeds of which provided schooling for many local children, including Takeo.

[7] Owada received sponsorship from the Foreign Ministry to study at Trinity College, Cambridge in the United Kingdom where he earned a law degree in 1959[8] and later a doctorate of philosophy.

From 1979 to 1981, while serving as visiting professor at Harvard Law School, Owada "remain[ed] on the Foreign Ministry payroll with the title of Minister at the Embassy in Washington, and would resume his career with another plum posting the following year.

a member of the Whitney R. Harris World Law Institute's International Council, and a member of the Crimes Against Humanity Initiative Advisory Council, a project of the Harris Institute at Washington University School of Law in St. Louis to establish the world’s first treaty on the prevention and punishment of crimes against humanity.

In 1962, at age 30, Hisashi married 25 year-old Yumiko Egashira, introduced to him by a mutual friend and later employer Takeo Fukuda.

[20] A year later, their eldest daughter Masako was born at Toranomon Hospital in Tokyo,[21] followed by twins Reiko and Setsuko in the summer of 1966 in Geneva, Switzerland.

[11] In 1993, Hisashi's daughter Masako Owada, a diplomat in her own right, married Crown Prince Naruhito, the heir to the Japanese Chrysanthemum Throne.