Okabe Seiichi graduated from Tokyo University (1895) and compiled the army's official chronicle of the Sino-Japanese War.
Okabe Seiichi was instructor at the First Higher School and a government compiler of historical documents of the Meiji Restoration (1868). Also taught history at Kokugakuin and Nihon Women's colleges. Helped organize the Japan History and Geography Society. Also compiled a biography of Takayoshi Kido, a Meiji Era statesman.