The 5th's principal bomber unit was the 4th Air Group that flew Mitsubishi G4M Type 1 "Betty" bombers. Twenty-four of the fighter aircraft in the 5th belonged to the Tainan Kōkūtai under Captain Masahisa Saito. The Tainan contained some of the top-scoring Japanese fighter aces and flew the A6M2 Zero fighter. With 55 pilots and 24 aircraft, only the most experienced and able Tainan pilots were allowed to consistently participate in combat operations. The dive bombers (Aichi D3A1 "Vals") and the rest of the fighters (A6M3 Zeros) belonged to the 2nd Air Group. Most of the dive bombers were lost during the 7 and 8 August strikes on the Allied landing forces. On 7 and 8 August, the Misawa Air Group of the 6th Air Attack Force (also called the 26th Air Flotilla) under Vice Admiral Seigo Yamagata from Tinian with 27 Type 1 bombers joined the 5th Air Attack Force at Rabaul. Around the same time, Admiral Tsukahara moved from Tinian to Rabaul to directly supervise air operations against Allied forces around Guadalcanal.