The studio was formed in the early 1980s as Daicon Film by university students Anno Hideaki, Sadamoto Yoshiyuki, Yamaga Hiroyuki, Akai Takami, Okada Toshio, Takeda Yasuhiro, and Higuchi Shinji. Their first project was to make an animated short for the 20th Annual Japan National SF Convention, also known as Daicon III, held in 1981 in Osaka, Japan. The group made a much bigger splash at the 22nd Annual Japan National SF Convention, Daicon IV, in 1983.
The Daicon IV short firmly established Daicon Film as a talented new anime studio. The studio changed its name to Gainax in 1985, basing the term 'Gainax' on an obscure Tottori Prefecture term for 'giant' and the English suffix 'x'.
Since Gainax originated as a group of fans, it was known for maintaining ties to the general otaku community, allowing doujinshi of its work, fan-made action figures, and promoting series like Evangelion at private festivals and so on.
Until Neon Genesis Evangelion, Gainax typically worked on stories created in-house, but the studio increasingly developed anime adaptations of existing manga like Kareshi Kanojo no Jijou and Mahoromatic.
The Animage Anime Grand Prix has been awarded to Gainax for Nadia: The Secret of Blue Water in 1991, Neon Genesis Evangelion in 1995 and 1996, and The End of Evangelion in 1997.
Much of Gainax's former staff and series left Gainax starting in the late 2000s; notably Anno Hideaki formed Studio Khara and obtained the rights to Evangelion, several staff members (including those involved in Tengen Toppa Gurren Lagann) left to make Studio Trigger, and Gainax sold their rights to FLCL to I.G. Production. Gonzo is also made of former Gainax staff, having left in the early 90s.
On May 29, 2024, Gainax filed for bankruptcy with the Tokyo District Court, which was publicly announced over one week later on June 7. The remainder of its properties were split between the various Gainax splinter companies and former staff previously mentioned.
