The six Nagara-class light cruisers were a class of six light cruisers built for and operated by the Imperial Japanese Navy. The Nagara-class cruisers proved useful in combat operations ranging from the Aleutian Islands to the Indian Ocean throughout World War II. Most served as flagships for destroyer or submarine squadrons, and were deployed for transport or local defense missions. Towards the end of the war, the surviving vessels were increasingly obsolete and were retained as second-line units.

The Sendai-class light cruisers were a class of three warships operated by the Imperial Japanese Navy. The vessels in the class were named after rivers according to the navy's light cruiser naming rule. They participated in numerous actions during the Pacific War and were mainly used as destroyer flotilla leaders.