The primary operator is the Japan Ground Self-Defense Force (JGSDF), who originally procured the OH-1 as a domestically produced successor to their existing OH-6D Loach fleet.

[2] In addition to its use as an observation helicopter, it can also be armed to directly participate in combat; such weapons include a limited quantity of air-to-air missiles for self-defense purposes.

[4] During the late 1980s, the JGSDF developed a requirement for a new scout/observation helicopter to replace its Kawasaki license-built OH-6Ds, which became the OH-X programme.

In 1991, Kawasaki's proposal was selected by the JGSDF's Technical Research and Development Institute as the prime contractor for the OH-X programme.

[1][6] This figure was significantly fewer than the 297 OH-6Ds that were in active service by March 1995, and there were repeated concerns that numbers could be further curtailed as a result of the impact of defense budget cuts.

[1] During the 1990s, the JGSDF was interested in procuring a new attack helicopter during the following decade, seeking to replace the Fuji-built Bell AH-1 Cobra fleet.

[12][13] The OH-1 had been intentionally designed with additional margin to accommodate such growth of scope, the main limiting factors being its transmission and engines.

[1] In 2005, Kawasaki proposed the development of a utility-orientated derivative of the OH-1 in response to the fledgling UH-X programme, which intended to replace the JGSDF's outdated fleet of Fuji-built Bell UH-1J Iroquois helicopters.

[15] This variant, which would have used the OH-1 as a base, would have featured a new cabin, avionics, transmission and engines, but would have also retained a high level of commonality between the observation and utility models.

[18] In July 2015, the Japanese Ministry of Defense (MoD) announced its decision to accept a rival bid made by Fuji/Bell to domestically produce a modified version of the Bell 412 to meet the UH-X requirement instead.

[7] In late 2008, Kawasaki was considered implementing a series of improvements aimed at increasing the payload of OH-1; this proposed modification was dependent upon demand from the Japanese defense ministry.