Japanese cruisers had three doctrinal roles. They gathered intelligence while screening friendly movements from enemy observation. In battle they might add gunfire against opposing capital ships to offset numerical inferiority. Long-range torpedo attacks and action against enemy destroyers or cruisers could instead protect the Japanese battle line and let its capital ships concentrate on their principal targets.
Chapter · 23:59-25:50
Three cruiser roles in the decisive-battle plan
Japanese cruisers were expected to scout, screen the fleet, and support the battle line with guns or torpedo attacks.