Admiral Arima Ryōkitsu (有馬 良橘, December 16, 1861 – May 1, 1944) was a career naval officer in the Imperial Japanese Navy during Meiji and Taishō periods.

From March 1900, Arima was assigned as chief navigation officer to the flagship of the Imperial Japanese Navy, the battleship Mikasa, on which he again visited England in 1902.

After his return to Japan, he was promoted to the position of executive officer on the cruiser Tokiwa, but at the end of 1903, he was reassigned to the staff of the IJN 1st Fleet.

In 1903, Commander Arima developed a military strategy which considered attrition as an element of overwhelming force in warfare; and this analysis caught the attention of Admiral Tōgō Heihachirō in the period shortly before the outbreak of hostilities in the Russo-Japanese War.

He served as Chief of First Bureau (Operations) on the Imperial Japanese Navy General Staff from 1910 to 1912 and at the end of 1913 was promoted to vice admiral.

[9] From 1914 to 1916, he was Commandant of the Imperial Japanese Naval Academy, continuing to influence its curriculum heavily towards the kantai kessen theory which he had helped create.

[15] However, he maintained close personal ties to Emperor Hirohito and Empress Kojun, serving as a chamberlain from 1939, and resigned from his post as chief priest of Meiji Shrine from 1943.