A technological innovator during its time, Kisaragi was always at the forefront of new inventions and breakthroughs. The company's research and development department was extremely successful at solving difficult problems and created many innovative AC-related parts. Unfortunately, their relatively small size made it difficult to actively compete against Mirage and Crest. They have been on various occasions threatened to either break up or be destroyed, and they often take precautions to avoid direct confrontation or much competition with the other two larger corporations.
On several occasions, however, they have cooperated with the other corporations, such as the development of the unmanned AC in Armored Core 3 with Mirage. However, they do not hesitate to do what is necessary (albeit covertly) to sabotage Mirage and Crest when they can. An example of this behavior can be seen in the mission "Destroy Naire Bridge." They are also known to have been specializing in the development of bio-weapons, as seen in Armored Core 3; in fact, in Armored Core: Last Raven, even after the formation of Alliance, a small branch loyal to Kisaragi continue their bio-technology research and improve the AMIDA bio-weapons first seen in Armored Core: Nexus.
During the events of Armored Core: Nexus, Kisaragi takes up a joint venture with Navis, but eventually parts ways as the Navis/Mirage conflict tenses further. After their destruction as a result of the relentless Attack of the Unmanned Suicide Weapons, Kisaragi merges with Mirage and Crest to form Alliance.