[3] In 2001, following its earlier proposal, the Kawasaki Aerospace Company received prime contractor status for the P-X program, as well as the adjacent C-X program for a next generation cargo aircraft; this selection process occurred almost 30 years since the previous large-scale domestic development of an aircraft in Japan.

[10] In April 2004, the JDA completed a successful evaluation of five XF7 research engines, by which point it was viewed as being the sole candidate powerplant for the P-X program.

[10][13] In April 2004, Japan and US extended discussions on potential cooperative efforts on the P-X and US Navy's Multi-mission Maritime Aircraft (MMA) programmes.

[17][18] New Zealand was the first country to which the P-1 had been offered, in what was referred to by a Japanese official as a "one on one fight with Boeing's P-8 patrol plane.

[24] One such key feature is the use of a fly-by-optics flight control system, which essentially replaces standard metal wiring with optical fiber cables.

[25][26] The P-1 is equipped with sensors to enable the aircraft to perform its primary purpose of detecting submarines and surface vessels.

[27] The P-1 is furnished with a CAE Inc.-built magnetic anomaly detector (MAD) embedded into the aircraft's tail,[24][28] along with deployable sonobuoys, which is used for the detection of submerged submarines.

[29] A large bomb bay housed within the main fuselage, similar in size to that of the Hawker Siddeley Nimrod's, contains the bulk of the aircraft's munitions.

[30][31] Weapons available on the P-1 include torpedoes, mines, depth charges, air-to-surface missiles (ASMs), such as the US-built Harpoon, or bombs.

[32] Multiple radar warning receivers provide all-round awareness of missile threats, which is combined with a defensive countermeasures suite.

[36][37] The rollout had been delayed for three months due to the discovery of defective rivets provided by a US supplier which required remedial repairs to be performed.

By March 2010, Kawasaki Heavy Industries had delivered four XP-1 maritime patrol test aircraft to Japanese Ministry of Defense.

The company stated its aim for type certification to be achieved in time for the formal delivery of the first two aircraft by the end of March 2012.

[15] On 26 March 2013, Japan's Maritime Self-Defense Force took delivery of its first pair of P-1s, ahead of a planned two years of test flights.

[50] In December 2018, the Japanese Ministry of Defense alleged that a Gwanggaeto the Great-class destroyer of the South Korean Navy locked its separate target illumination radar onto a P-1 belonging to Air Patrol Squadron 3.

[52][53][54] In September 2020, Germany was no longer considering the P-1 due to concerns the aircraft would not be able to achieve military type certification within a required five years time frame.

[59] In January 2015, it was reported that Tokyo was holding a series of defence talks with the United Kingdom to ascertain a possible sale of P-1s to the Royal Air Force, to replace their recently retired fleet of Hawker Siddeley Nimrod patrol aircraft.

It was claimed that Britain may consider jointly manufacturing the type, and that the nation could retain rights over related radar and sensor technologies.

[61][62] New Zealand requested information on the P-1 and Kawasaki C-2 to meet the country's patrol and transport aircraft needs.

This request was met with unclassified information in September 2016 and a more detailed proposal including purchase price, manufacturing arrangements, and maintenance complete by mid-2017.