Doctor of law
Okano was a native of Kōzuke Province (modern-day Gunma Prefecture). He graduated from the Kaisei Academy, followed by the Law School of Tokyo Imperial University, continuing on to graduate school to obtain a Doctor of law degree. He became professor of Tokyo Imperial University ("See "). He worked as a bureaucrat at various cabinet ministries in the Meiji government, and was appointed to a seat in the Upper House of the Diet of Japan in 1908. He served as Director-General of the Cabinet Legislation Bureau under the 1st and 2nd Saionji administration (1906–1908; 1911–1912), and the 1st Yamamoto administration (1913). From 1913 to 1922, Okano served as Secretary to the Administrative Court.