 In response to the Allied landings on Guadalcanal , the Japanese Imperial General Headquarters ( IGH ) assigned the Imperial Japanese Army 's ( IJA ) 17th Army , a corps @-@ sized command headquartered at Rabaul under the command of Lieutenant General Harukichi Hyakutake , the task of retaking Guadalcanal . Because of the threat by CAF aircraft , the Imperial Japanese Navy ( IJN ) was unable to use large , slow transport ships to deliver troops and supplies to the island . Instead , warships based at Rabaul and the Shortland Islands were used to carry forces to Guadalcanal . The Japanese warships , mainly light cruisers and destroyers from the Eighth Fleet under the command of Vice Admiral Gunichi Mikawa , were usually able to make the round trip down " The Slot " to Guadalcanal and back in a single night , thereby minimizing their exposure to CAF air attack . These high speed warship runs to Guadalcanal occurred throughout the campaign and were later called the " Tokyo Express " by Allied forces and " Rat Transportation " by the Japanese . 
