Ki-21 of the Daisan Dokuritsu Hikōtai at Yontan Airfield, 25 May 1945.
On November 24, 1944, it formation of B-29 bombers inflicted the first raid on Tokyo from the Marianas; and the 1st Raiding Bde was ordered to form a special unit for a commando mission. Japanese bombing of the Marianas airfields was insufficient to delay the construction of USAAF bomber bases; the IGHQ planned to send airborne commandos to crash-land on the Saipan airfields and destroy the B-29s. Captain Michiro Okuvama was selected to lead the special unit; he was the commander of the 1st Raiding Regt's Engineer Co, trained in sabotage and demolition techniques. Other soldiers of the regiment who had missed earlier operations were also eager for action. Captain Okuyama had been the first member of the original IJA parachute training unit; this outstanding and highly respected officer was entrusted by brigade HQ with choosing the 126 men for what he knew was a suicide mission. He selected most of them from his own company; later, the special team was named Giretsu Airborne Unit (Giretsu Kuteitai) Giretsu means "respect for faith." It was organized as a command section (Capt Okuvama) and five platoons 1st Plt (Lt Utsuki), 2nd (Lt Sugata), 3rd (Capt Watabe), 4th (Lt Murakami) and 5th (Lieutenant Yamada.)On December 5 the unit moved to the IJA air academy at Saitama, Kanto. There ten intelligence officers, experts in sabotage, joined them from the Nakano intelligence school; two were assigned to each platoon, bringing total strength to 136. The unit was placed under the direct command of the Leading Air .Army. At Saitama a mock-up of a B-29 was prepared. Type 99 magnetic charges could not clamp to the aircraft's aluminium skin, so two types of special weapons were developed. One had a 2kg (4.41b) explosive charge at the end of a pole; a rubber suction cup was attached on the top of the charge. Gripping the pole, the raider pushed it up under the B-29's wing, and pulled a cord to ignite the delay fuse. The other weapon was the chain charge, a 13-16ft rope with explosive charges attached along its length; a small sandbag weight was attached to one end, to aid throwing it over the aircraft's fuselage or wing.
December 6, Clark Field: two fully loaded paratroopers await the order to board the aircraft for Okinowa. The medical aid man (eiseihel) has haversacks packed with medical supplies rigged as leg bags; note that the Japanese, like Christian nations, used the Red Cross emblem.
The Giretsu commandos began intense training; Capt Okuyama stressed that each man must destroy two or three planes at least, even if he was mortally wounded in the process. On December 22 the Giretsu Unit conducted a demonstration for senior staff; the commandos ran swiftly through the darkness as though it were daylight, and skilfully attached their explosives to planes. The observers were impressed by a performance worthy of Ninjas. Although the Giretsu commandos were ready, the preparation of the air transport unit was delayed. The 3rd Independent Flying Unit (Capt Suwabe) was assigned to deliver the Giretsu Unit, converting from their previous Type 100 scout aircraft on to Mitsubishi Type 97 "Sally" bombers. The pilots were inexperienced with these new aircraft and not yet able to conduct long range flights over water. The attack was nevertheless scheduled for January 17th, 1945, and the commandos moved to Hamamatsu airbase on Honshu. However, American raids damaged the planned refuelling airfields on Iwo Jima (Type 97 bombers had insufficient range to fly to the Marianas direct from Japan), and the operation was cancelled. The disappointed Giretsu commandos returned to Nyutabaru and the 1st Raiding Brigade. After the Marianas raid was cancelled plans were made to attack airfields on Iwo Jima captured by the US Marines in March, but these too were cancelled when the Iwo Jima garrison fell. The Giretsu Airborne Unit was not disbanded, however, and the commandos remained willing and ready. This period was difficult for them: as a suicide unit they were especially well treated, but these privileges were a burden for the waiting commandos. On April 1st, US forces landed on Okinawa, and American fighters deployed to the captured Yontan (Japanese, Yomitan) and Kadena airfields on Okinawa's west coast intercepted and shot down many kamikaze planes attacking the American fleet. On May 15th, 6th Air Army (former Leading Air Army) requested that IGHQ allow the use of the Giretsu Unit to neutralize these airfields. The commandos and the 3rd Independent Flying Unit moved to Kengun airfield on Kyushu to prepare for what was designated the Gi Operation. The flying unit provided 16 x Type 97 bombers and four in reserve, stripped of guns to save weight. Eight would carry Capt Okuyama with his 1st, 2nd & 5th Pits to Yontan; another four were assigned to take Capt Watabe and 3rd & 4th Pits to Kadena. The plan was for the force to take off from Kengun in the evening, and crash-land on the US airfields before midnight. The raiders would destroy aircraft and facilities, and then take up positions nearby to prevent enemy use of the airfields with automatic weapons fire. Almost 50 IJA and IJN bombers and fighters would attack the target airfields before the commandos landed, in hope of distracting the Americans from the approach of the raiders' aircraft. Next day, with the US fighter fields neutralized, some 180 IJN and IJA kamikazes and over 30 conventional attack aircraft (some bearing Ohka piloted flying bombs) would attack US shipping.
The detailed organization of the Giretsu Unit was as follows; besides the listed weapons, each commando carried HE and WP grenades plus a pistol:
Command section (10 men)
LMG team (1x LMG)
1st-5th Platoons, each of two Sections, each of:
1st Team (4 men including section leader): 1x Type 99 rifle, 2x Type 100 SMGs, 2x pole charges, 4x Type 99 AT charges
2nd Team (3 men): 1x rifle, 1x Type 99 LMG, 1x pole charge, 4x Type 99 AT charges
3rd Team (3 men): 1x rifle, 1x SMG, 1x pole charge, 4x Type 99 AT charges
4th Team (3 men): 1x rifle, 1x SMG, 1x Type 89 grenade discharger, 1x pole charge, 4x Type 99 AT charges.
Afternoon of December 6, Clark Field: "Takachiho paratroopers" boarding a Type 100 transport; some are carrying their leg bags, for attachment once they are aboard. They wear Type 4 (1944) parachutes - note the single-point attachment for the suspension lines. There were reports that when they jumped over Buri airfield some of the paratroopers' harness releases failed and they fell from their parachutes in mid-air.
The attack was planned for May 23, but had weather over Okinawa forced its postponement by a day. When the commandos assembled on the airfield their spirits were high, although they did not expect to return. After a brief ceremony they boarded the planes, and at 1850hrs on May 24th the 12 bombers took off and headed southwest on the 480-mile flight to Okinawa; four of them aborted, however, returning to base with engine problems. On the departure airbase men waited around a speaker connected to the radio room. At 2210hrs they heard a message from the Giretsu Unit "Now, I land!' - and they shouted with joy. About a half-hour later US radio traffic indicated an emergency at Yontan airfield, where Japanese aircraft reported a huge fire. As kamikazes attacked radar picket ships, attack aircraft made their runs on the airfields beginning at 2000hrs, and in their wake the bombers carrying the Giretsu commandos roared in at low level. US Marine and Army AA battalions opened fire, downing 11 twin-engine aircraft. Bombs intended for Yontan, the base for Marine Air Group 31, missed the airfield. At 2125 a “Sally” made a run much lower than previous attacks, and was shot down. At 2230 three more approached, apparently thing to land; then too were brought down, crashing near the field, but a small number of the Japanese commandos survived and rushed to accomplish their mission. One bomber’s wing struck an AA gun position, burying the crew and killing two of them. A fifth “Sally” belly-landed on the NW/SE runway, sliding to a halt 80 yards from the control tower; an estimated 12 commandos dashed from this plane, throwing grenades and demolition charges and firing their weapons. Two fuel dumps were set alight, with the loss of 70,000 gallons. Pandemonium reigned as Marine ground crewmen, AA gunners and security troops opened fire in all directions; this indiscriminate firing caused most of the Americans’ 18 wounded and one killed, and some of the aircraft damage. All of the commandos were killed; the last being discovered at 1255hrs the next day hiding in the brush. In all, 69 Japanese commandos and airmen were buried; some had committed suicide. US aircraft losses were three F4U Corsair fighters, two four-engine PB4Y Privateer patrol bombers, and four R4D ((C-47) transports. Another 22 F4U's, three F6F Hellcat fighters, two PB4Y's and two R4D's were damaged. Japanese kamikaze attacks were launched on May 25 and 27, but it could not be determined by the Japanese if the Yontan attack had had a significant effect on the numbers of American fighters defending the fleet, large numbers of which were still available. Yontan was operational again on the afternoon of the 25th, and most damaged aircraft were repaired within days.