小笠原氏
Ogasawara was born in Saga prefecture. His father was the Rōjū Ogasawara Nagamichi, a senior retainer of the Tokugawa shogunate. As his father was forced into retirement by the events of the Boshin War of the Meiji Restoration. Ogasawara Naganari succeeded his grandfather to become head of the Ogasawara clan in 1873, and as viscount ("shishaku") under the "kazoku" peerage system. He attended the Gakushuin Peers’ School, and subsequently graduated 35th out of 45 cadets at the 14th class of the Imperial Japanese Naval Academy. One of his classmates was the future Prime Minister of Japan Kantarō Suzuki.