Born in Ishikawa Prefecture, to a samurai-class family formerly in service to Kaga Domain, Hayashi dropped out of school in July 1894 to enlist in the Imperial Japanese Army at the start of the First Sino-Japanese War. After the end of the war, he attended the Imperial Japanese Army Academy, and on graduation in June 1897 was assigned to the IJA 7th Infantry Regiment. in 1903, he graduated from the Army Staff College. With the start of the Russo-Japanese War, Hayashi participated in the Siege of Port Arthur.