I-18 was one of five Type C cruiser submarines of the C1 sub-class built for the Imperial Japanese Navy. During World War II, she operated as the mother ship for a midget submarine during the attack on Pearl Harbor and the attack of Diego-Suarez, conducted a war patrol in the Indian Ocean, and served in the Guadalcanal campaign before she was sunk in February 1943.

Sasebo Naval Arsenal was one of four principal naval shipyards owned and operated by the Imperial Japanese Navy.