 His father had various high-level positions in the Ministry of Foreign Affairs and Imperial Privy Council, leading up to Ambassador to China's Qing Dynasty during the Boxer Rebellion.Nishi went to Gakushuin pre-school and, while in elementary school, repeatedly got into fights with students of nearby Bancho elementary school.In 1912, at the age of 10, he succeeded to the title of Baron upon the death of his father.