After graduation from the university Otani studied in America and Europe.
Returning home Otani served in turn as chief of Taxation Office, Parliamentary Vice-Minister of Finance, instructor at Chiio University and vice-president of Hochi Shimbu (newspaper).
After World War II, he left politics and entering the business field to become president of Takai Industrial Company in 1950. Then Otani served as chairman of Shonan Department Store.
Otani entered politics and was elected to the Diet six times. After World War II, he left politics.