Although classified officially rated as a tsūhōkan, meaning dispatch boat or aviso, the class were essentially small protected cruisers.

[1] The Yodo-class cruisers were designed and built domestically in Japan, having been ordered as part of the 1904 Emergency Fleet Replenishment Program to recover from losses to the Japanese navy from the Russo-Japanese War but were not laid down until after the war had ended with the Treaty of Portsmouth due to delays in construction.

Another significant difference between the two ships was their propulsion systems, while Yodo had a conventional two shaft, four cylinder reciprocating (VTE) engines with four Miyabara boilers, Mogami has the distinction of being the first Parsons-type turbine-powered vessel in the Imperial Japanese Navy.

[1] Two ships were budgeted for and completed under the 1904 Emergency Fleet Replenishment Program, one each from the Kawasaki Shipyards, Kobe and Mitsubishi Yards, Nagasaki.

Initially assigned to training and coastal duties, Mogami was reclassified as a first class gunboat on 12 October 1912.

Mogami was part of the Japanese fleet at the Siege of Tsingtao in World War I, and assisted in the sinking of the German torpedo boat S90.