Gainax was founded in 1984 when seven university students including Hideaki Anno, Yoshiyuki Sadamoto, Hiroyuki Yamaga, Takami Akai, Toshio Okada, Yasuhiro Takeda, and Shinji Higuchi formed Daicon Film. The group officially changed their name to Gainax in 1985 based on an obscure term from Tottori Prefecture meaning giant.
The National Tax Agency audited Gainax on suspicion of tax evasion after investigations revealed the company concealed ¥1.56 billion worth of income between Evangelion's release and July 1997. These payments ostensibly covered animation expenses but resulted in 90% of the sums being withdrawn as cash and stored in safe deposit boxes.
Takeshi Sawamura served as president when the scandal broke and was arrested alongside tax accountant Yoshikatsu Iwasaki on the 13th of July 1999. Both men were later jailed for accounting fraud involving unpaid corporate taxes totaling ¥560 million.
On the 7th of June 2024, Gainax announced it had filed for bankruptcy on May 29 citing financial mismanagement decisions and substantial debt accumulation. The company officially ceased all operations that same day before being formally dissolved on the 11th of December 2025.
The Gainax trademark transferred to Khara who instructed remaining properties be returned to their rightful owners instead of scattered among debt collection companies. Hideaki Anno recapitulated the mismanagement by co-founders in a public statement thanking Yasuhiro Kamimura for meticulous handling of financial issues.