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. In 1915, he entered Tokyo First Junior High School (now Hibiya High School) in accordance with the dying wishes of his father; his classmates included Hideo Kobayashi, future pre-eminent literary critic, and Hisatsune Sakomizu, who would be Chief Cabinet Secretary in 1945.