Toyoda returned to school, becoming a torpedo and naval artillery expert. As a lieutenant from 1 December 1911, he served on the battlecruiser . He graduated from the Naval War College (Japan) with honors in 1915, and was promoted to lieutenant commander on 1 April 1917. From 1917 to 1919, he was "aide-de-camp" to Admiral Motaro Yoshimatsu (:ja:吉松茂太郎). From 1919 to 1922, he was sent as naval attaché to the United Kingdom, during which time he was promoted to commander on 1 December 1921.