In a brief interview with Reuters at an undisclosed location in Tokyo, Hamanaka also said that he would comment on the scandal "some time in the future".
He said he had had no contact with his former employer since he was fired on 14 June, a day after the company announced that it had lost $1.8bn due to what it said were unauthorised copper trades, mainly by Mr Hamanaka. The interview was his first since the affair broke. His location since then has been a mystery.
He appeared relaxed despite the swirl of publicity around him after his company alleged that he was the main cause of the biggest financial scandal in history. But he refused to discuss the case.
"I don't want to make any comment on that issue. I will talk to you in detail at the right time in the future," he said.
A spokeswoman for the Serious Fraud Office yesterday refused to comment on Mr Hamanaka's emergence, as the SFO has a policy of not talking about operational details of its investigations.
She did, however, say that three members of the SFO visited Japan at the end of June over the Sumitomo scandal. "We did this to set up lines of communication with the Special Procurator's Office (the Japanese equivalent of the SFO). Our working relationship with them so far has been very productive and cordial."
Mr Hamanaka has broken his silence days after the SFO raided the English country homes of the two heads of Winchester Commodities Group, as part of its probe into the Sumitomo scandal.
Winchester, which was the primary UK metals broker for Hamanaka in the early 1990s, was investigated last year for its business with the Japanese trader. The investigation was dropped earlier this year but was restarted after the Sumitomo scandal broke in June.
The homes of Charles "Copperfingers" Vincent and Ashley Levett in the southern county of Hampshire were searched on Wednesday and documents were taken by Fraud Office investigators.
Both Mr Vincent and Mr Levett, who spend most of their time at their homes in Monaco since retiring last year, were away from England at the time of the searches.
The SFO would not comment on what it was looking for or even on the names of the owners of the homes.
"Officers from the Serious Fraud Office and the City of London police executed search warrants on two residential premises in Hampshire yesterday as part of an ongoing investigation into the copper trading market,'' a spokeswoman said in a statement.
Winchester spokesman John Kiely also would not comment on the searches, except to say that "we've said all along we would fully co-operate with any investigations and that continues to be the case".
The searches represent an increase in activity by investigators in the two-month-old Sumitomo copper scandal.
The SFO is conducting its investigation in tandem with the UK's Securities and Investments Board and the Commodity Futures Trading Commission in the US. Sumitomo is conducting its own investigation and has said that it will complete it within six months.
Separately, the Securities and Investments Board said it would release a consultative paper in the next few days.