海軍兵學校
In September 1876, Tomioka enrolled in the 5th class of the Imperial Japanese Naval Academy and graduated at the top of his class. In 1878 he was sent as a cadet to serve on the Royal Navy warship HMS "Audacious". After his return to Japan, he graduated from the Navy Staff College. During the First Sino-Japanese War, Tomioka served as executive officer on the cruiser . He subsequently served as captain of the dispatch ship , instructor at the Imperial Japanese Naval Academy, captain of the cruiser and of the battleship and director of the 1st Bureau of the Imperial Japanese Navy General Staff.