The Imperial Japanese Army developed the Ka-1 autogyro for reconnaissance, artillery-spotting, and anti-submarine uses. The Ka-1 was based on an American design, the Kellett KD-1A, which had been imported to Japan in 1939, but which was damaged beyond repair shortly after arrival. The Kayaba Industry was then asked by the Army First to develop a similar machine, and the first prototype was flying on 26 May 1941. The craft was initially developed for use as an observation platform and for artillery spotting duties. The Japanese Army liked the craft's short (30m) take-off span, and its low maintenance requirements. The production began in 1941 and the first autogyros were assigned to artillery units for artillery spotting. These carried two crewmen: a pilot and a spotter. The prototype, Ka-1 was essentially the repaired Kellett KD-1A. The Ka-1 had a change of the engine to the 240 hp Argus As 10c. But only about 20 Ka-1 were made. The Ka-1 employed similar aspects to the Focke-Wulf Fw 61, which was first flown in 1936. The production of the remainder were all Ka-2. The Ka-2 returned to the same Jacobs L-4MA-7 engine as the Kellett KD-1. Total Ka-1 and Ka-2 production was erroneously stated as approximately 240 by. During the production, a shortage of critical components for rotor and engine resulted in severe delivery delays. A total of 98 Ka-1 and Ka-2 airframes were produced until end of war, of them 12 was destroyed by exposure before being delivered to army and about 30 never had an engine installed, leaving about 50 delivered to IJA and about 30 actually deployed.Japanese wiki
Japanese wikipedia page The repaired Kellett KD-1A first took off from Tamagawa Airfield in May 26, 1941. In the following army trials, performance was deemed excellent. Originally, it was planned to send Ka-1 to the artillery units in mainland China, but the change of the course of war have made these plans meaningless. Instead, few Ka-1 were sent to Philippines to perform duties of liaison aircraft as replacement of Kokusai Ki-76. The majority of Ka-1 and Ka-2 was pressed to the anti-submarine patrol duties. Pilots training have started in July 1943 and first batch of 10 pilots have graduated flight school in February, 1944 followed by another batch of 40 pilots in September, 1944. Originally, Ka-1/Ka-2 was planned to deploy from 2D class cargo ships, but these ships turned out too cramped for operations, therefore Ka-1/Ka-2 unit was assigned to escort carrier Akitsu Maru from August 1944 to her sinking in November 1944. From 17 January 1945 ASW patrols have resumed from airstrip on Iki Island with maintenance base being Gannosu Airfield in Fukuoka prefecture. ASW patrols also started from in May, 1945 from Izuhara airfield on Tsushima Island. These missions helped to protect last operational Japanese sea lane between ports of Fukuoka and Pusan. Because USA carrier-based aircraft have started to appear even in Tsushima Strait, the Ka-1/Ka-2 units were relocated to Nanao base on Noto Peninsula in June, 1945 and operated there until end of war. The Ka-1/Ka-2 did not sank directly any submarine during war, but were regarded well-performing for their help in issuing submarine warnings.