Mogami was the lead ship in the four-vessel Mogami class of heavy cruisers in the Imperial Japanese Navy. The Mogami-class ships were constructed as "light cruisers" with five triple 155-millimetre (6.1 in) dual-purpose guns. They were exceptionally large for light cruisers, and the barbettes for the main battery were designed for quick refitting with twin 8-inch (203 mm) guns. In 1937, all four ships were converted to heavy cruisers in this fashion. Mogami served in numerous combat engagements in World War II, until she was sunk at the Battle of Leyte Gulf in October 1944.