From Game Developer Research Institute
Crux (クラックス) was started from the ashes of Orca after that company went bankrupt and was thrown out of its building. Crux would eventually go bankrupt as well due to management difficulties. The chief programmer on Gyrodine and two others left for Toa Kikaku and started a software division which became Toaplan. Tatsuya Uemura (上村建也) was invited over, but did not leave until after he finished working on Repulse. 
Crux was headed by Takeshi Tozu (戸津猛), who previously ran Orca and later ran Whiteboard/Santos. (Game Machine 1983/8/15, pg. 6) 
Research Methods: Online resources
- Gyrodine (Taito)
- Repulse (Sega)
- Taichi (unreleased)
- Development started at Orca, but continued at Crux. There was a location test.