Olympus Corp's former president, Tsuyoshi Kikukawa, has admitted guilt in a cover-up of massive investment losses at the Japanese camera and medical equipment maker.
The scandal emerged last year when Michael Woodford, the British chief executive who turned whistleblower, raised questions about payments for financial advice and dubious acquisitions. Mr Woodford was later fired.
"There is no mistake. The entire responsibility lies with me," Kikukawa told the Tokyo court.
Tokyo prosecutors have charged the company, Kikukawa and other officials, arrested in February, with violating laws regulating securities exchanges by falsifying company financial statements.
Three other Olympus executives also pled guilty today. The company also entered a guilty plea.
If found guilty, individuals face up to 10 years in prison, a Y10 million ($123,495) fine, or both. The company can be penalised with a fine of up to Y700 million.
Olympus has said it hid Y117.7 billion in investment losses dating to the 1990s.