Nakajima J1N "Gekko" (Irving), 153 Kokutai

A set of photos feature Nakajima J1N "Gekko" (Irving) flown by the 153 Kokutai as indicated by the numbers "153-" and "53-" on the aircraft tails.

A late-model Nakajima J1N "Gekko" (Irving) Model 11 (J1N1-S) with the step on the dorsal fuselage removed. This particular aircraft has had its downward-facing guns removed.

The same Nakajima J1N "Gekko" (Irving) Model 11 (J1N1-S) seen in the previous photo. On January 5, 1945, this "Gekko" of the 153rd Kokutai, Sento 851 Hikotai, made an emergency landing at Taisho Army Airfield in Osaka due to engine trouble. The drop tanks under the wings were the same type as those used on the Zero fighter (300 liters capacity) and were painted light gray. The crew, consisting of Chief Petty Officer Takano and LTJG Hayashi, and others received eight aircraft, including this one, at Atsugi Air Base. Two of the aircraft, including Hayashi's, landed at Taisho on their way to Kanoya. They departed the following day, the 6th, and headed to Taiwan via Kanoya to rendezvous with the main force. Because all the aircraft stationed at Clark Air Base in the Philippines, where they were scheduled to deploy, had been withdrawn, the 851 remained in Taiwan.

A Nakajima J1N1-Sa "Gekko" (Irving) captured by US forces at Clark Air Base. The inspection/maintenance hatch is open, and the hole through which the barrel of the Type 99 Model 2 cannon protrudes is clearly visible. The photograph was taken on February 12, 1945, one month after the defeat in the air battles over the Philippines. It is believed to be an aircraft of Sento 812 Hikotai, the last "Gekko" unit to advance under the command of the 153rd Kokutai.

The same Nakajima J1N1-Sa "Gekko" (Irving) captured by US forces at Clark Air Base.

Sometimes the aircraft in this photo is identified in various sites and FB pages as a Kawasaki Ki-45 "Toryu" (Nick).  

One more photo of the same Nakajima J1N1-Sa "Gekko" (Irving) captured by US forces at Clark Air Base. 

Artwork by Kuroki Hitomi, of the previously seen Nakajima J1N1-Sa "Gekko" (Irving) captured by US forces at Clark Air Base, featured in FAOW #57. 

Below is a set of photos featuring another 153 Kokutai "Gekko", tail code "153-71" captured by US forces at Clark Air Base. 

Note the "H-6" (officially the Type 3 Airborne Radio No. 6) radar antennae protruding from the fuselage sides. The H-6 was the most widely deployed radar for Japanese Navy aircraft, seeing extensive use in maritime search and patrol missions from 1944 onwards. It operated on a wavelength of 2 meters (150 MHz); specifications indicated a detection range of 95 km for large ships and 55 km for a single large aircraft.

Approximately 2,000 units of the H-6—which utilized a maximum-sensitivity detection method—were manufactured by Japan Radio Co. and Kawanishi.

Unit history from the Japanese Wikipedia:

As land battles in New Guinea intensified and a counteroffensive by the U.S. Army—which had been rebuilding its forces in Australia—loomed, there arose a need for long-range reconnaissance units operating on the front lines stretching from western New Guinea to eastern Dutch East Indies. The 753rd Kokutai, which had long been based at the Kendari airfield on Celebes Island and was responsible for bombing missions toward the strategic stronghold of Darwin, had also been performing long-range reconnaissance duties; however, it was being severely depleted without ever being able to return to the home islands. Consequently, the 153rd Kokutai was formed as a new unit dedicated exclusively to reconnaissance. However, initially, they were unable to procure reconnaissance aircraft. Consequently, even though they had a full complement of personnel, they could not conduct reconnaissance missions and could do little more than analyze and relay reconnaissance information obtained from Army air units. 

January 1, 1944: Established at Kendari Airfield with Hsinchu Airfield as its home base (authorized strength: 12 land-based reconnaissance aircraft; however, no aircraft were available initially).

Directly under the command of the Southwest Area Fleet and the 13th Air Fleet.

By March, reconnaissance operations began using Mitsubishi Ki-46 "Dinah" transferred from the Army. In early March, Yokosuka D4Y "Suisei" (Judy) arrived from the mainland.

March 5, 1944: Reconnaissance of southern New Guinea conducted with two "Suisei".

March 10, 1944: Reconnaissance of New Guinea commenced every 10 days using "Dinah".

March 30, 1944: Engaged in patrol and search operations over the waters north of New Guinea following the Palau Air Raid. Operations continued until the alert was lifted on April 8.

April 9, 1944: Ordered to advance into New Guinea; moved to Wakde Island Airfield off the coast of Biak Island. Began patrols on the 13th.

April 22, 1944: Ground operations began in Hollandia.

May 4, 1944: Reconnaissance of Hollandia after its fall; reported on the status of airfield repairs.　　　　　

Around this time, the Sento 311 Hikotai was incorporated, forming a mixed fighter-reconnaissance unit. 

Early May 1944: Withdrew to Sorong (Jefman) Airfield, the westernmost point of New Guinea. Avoided the ground battle on Wakde Island that began on the 18th.

May 25, 1944: Incorporated 12 aircraft from the 201st Kokutai, which was undergoing training in Davao.

May 27, 1944: The "First Operation Kon" was launched (Operation Kon was a three-stage Japanese military operation designed to support the Battle of Biak Island). Engaged in air patrol until the order to cease operations on June 3.

Dispatched two fighters from the main force to escort the 24th Sentai bombing enemy positions on Biak Island.

June 5, 1944: "Operation Kon II" launched. Resumed patrol duties along shipping lanes.

June 7, 1944: Ordered the entire unit to withdraw to Kendari. Abandoned equipment and withdrew from "Operation Kon".

Thereafter, engaged in reorganization efforts.

July 10, 1944: A major reorganization of the kokutai was carried out. Placed under the direct command of the First Air Fleet and withdrew to Davao.

Transferred the Sento 311 Hikotai to the 201st Kokutai and incorporated the disbanded 251st Kokutai as Sento 901 Hikotai.

July 25, 1944: As the first batch of procured aircraft, four "Suisei" and nine "Gekko" arrived in Manila.

Throughout August, patrol operations were impossible due to a shortage of aircraft, so the unit focused solely on analyzing intelligence from the Army’s 15th Sentai.

September 1, 1944: Air raids on Davao began.

September 2, 1944: Another air raid on Davao. Four "Gekko" engaged the enemy. Three "Suisei" began patrolling for enemy task forces.

September 9, 1944: During the air raid on Davao, the "Gekko" used Type 3 cluster bombs but failed to shoot down any enemy aircraft, resulting in the loss of all aircraft.

Mid-September 1944: Two "Suisei" and eight "Gekko" aircraft advanced to Nichols Airfield on Luzon Island.

Upon arrival, both the "Suisei" and six of the "Gekko" aircraft were unable to conduct patrols due to mechanical failures. Patrols were carried out with the remaining "Gekko".

September 21, 1944: During a pursuit following the air raid on Manila, the enemy fleet was discovered; one aircraft was lost.

September 22, 1944: The remaining one aircraft guided the Zero Fighter Squadron of the 201st Kokutai.

October 27, 1944: The Davao detachment began supporting "Operation Tago" (a joint operation by the Japanese Army and Navy to transport reinforcements to Leyte Island during the Battle of the Philippines).

Late November 1944: Ran out of aircraft.

January 9, 1945: The First Air Fleet was ordered to withdraw to Taiwan.

The vast majority of the 153rd Kokutai personnel were unable to evacuate to Taiwan during the rescue operations that continued until February 10th, and were left behind in the Philippines. The 15,000 aircrew members of all the air units that could not evacuate formed the "Clark Area Defense Unit" under the command of General Sugimoto Ushio, commander of the 26th Air Fleet, and were deployed to ground combat under the 2nd Tank Division of the Army. Commander Wada Tetsujiro, who was in command of the 153rd Kokutai personnel on the ground, died of illness on October 29th after the surrender and did not survive to return home.