He graduated just weeks after the publication of the first and last chapters of Alfred Thayer Mahan's classic study, The Influence of Sea Power Upon History, 1660–1783 in its Japanese translation in July 1890.

On commissioning as an ensign on 23 May 1892, he rose through the ranks in a variety of routine shipboard assignments and duties that included deployments throughout the Pacific Ocean, Mediterranean Sea, and European waters.

Following the hostilities he served a tour at the Imperial Navy's Torpedo school and then was assigned to naval intelligence, where he spent several months posing as a laborer and conducting missions in Manchuria and Korea.

It was a time of heightened tension between Japan and the United States, due to the overthrow of the Kingdom of Hawaii by American marines and settlers, which nearly led to a rupture of diplomatic relations.

Akiyama then contacted the Assistant Secretary of the Navy, Theodore Roosevelt, but his pleas to be allowed to attend the Naval War College were refused.

In February 1899, due to the efforts of the Japanese ambassador, Akiyama received permission to serve a six-month tour on board a US Navy warship, the USS New York, where he was able to observe American tactics and fleet operations in the North Atlantic and Caribbean firsthand.

He also introduced the concepts of wargaming and tabletop map exercises, and developed theories for a new strategic and tactical doctrines for the Japanese Navy based upon his observations during the Spanish–American War.

Akiyama remained one of the few senior officers completely untouched by suspicion or corruption, and was nominated by Yashiro Rokuro as Director-General of the Navy in an effort to restore public confidence.

His major accomplishment during this period was to have the Otowa stationed permanently at Shanghai, from which it helped support a large network of intelligence agents posing as exchange students in all corners of China.

At the same time, Akiyama maintained a regular and secret correspondence with Sun Yat-sen, assisting him also materially in his efforts to prevent Yuan Shikai from establishing a new empire.

[5] With the outbreak of World War I, Akiyama traveled to Europe via the Trans-Siberian Railroad to Finland, and from there to England, where he met with his old acquaintance, former British naval observer Commander William Christopher Pakenham.

[8] He returned to Japan via the United States to assume command of the IJN 2nd Fleet in October 1917, but by this time he was already very ill, and was forced to retire in late 1917 with the rank of vice admiral.