Actor Kenji Haga is set to receive a six-year prison term for fraud after the Supreme Court dismissed his appeal of a lower court decision, judicial sources said Monday.

The top court rejected an appeal Thursday by the 51-year-old actor, whose real name is Mikio Toma, against the Osaka High Court's 2011 ruling that found him guilty of defrauding a man of ¥370 million and attempting to blackmail him.

Also Thursday, the Supreme Court upheld another ruling by the Osaka court sentencing former professional boxer Jiro Watanabe, 58, to two years in prison for conspiring with Haga in the blackmail attempt.

According to the high court ruling, in 2001 Haga swindled the man out of ¥370 million as payment for the unlisted stock of a medical consulting firm. The price was three times higher than the actual cost of the shares.

The actor conspired with Watanabe, a former world boxing champion, and others in 2006 to coerce the man into giving up his demand that Haga pay back part of the money.

In 2008, the Osaka District Court acquitted Haga on charges of fraud and attempted blackmail, citing doubts about the victim's testimony after a former dentist and acquaintance of the actor said the man knew about the actual price of the stock.

But the high court found the former dentist's testimony unreliable, as it was not supported by objective evidence and judged that he was being "intentionally deceitful" out of concern for Haga, with whom he had close ties.

The high court said the victim's testimony was "consistent with other facts and thus highly credible," and found both Haga and Watanabe guilty.

The former dentist was later convicted of perjury over his testimony at the district court.