Yamaichi Securities Co., one of the Big Four brokerages, has so far found no illegal transactions with the "sokaiya" corporate extortionist at the center of a growing financial scandal, the firm's chairman said July 1.

Tsugio Yukihira, speaking at a news conference as the newly appointed chairman of the Japan Securities Dealers Association, said in-house investigations have not revealed any wrongdoing. Yukihira's comments were effectively a denial of media reports that sokaiya Ryuichi Koike received paybacks through illegal discretionary accounts from three major brokerages, including Yamaichi.

"The probe is being led by our president, and I am not well informed of the details, but I intend to carry out my duties as association chairman," he said. Koike is the key figure in a widening financial scandal that has so far disgraced industry leader Nomura Securities Co. and the nation's second largest commercial bank, Dai-Ichi Kangyo Bank.

Many former and incumbent Nomura and DKB executives have been arrested on suspicion of providing illegal payoffs to Koike, and the scandal has shown the public how deeply such sokaiya have penetrated corporate Japan. Yukihira had been acting chairman of the industry body since mid-March, when then Nomura Chairman Masashi Suzuki stepped down as JSDA head after the scandal broke.

On June 30, media reports alleged Koike has told investigators that he received financial favors not only from Nomura, but also from the other Big Four firms -- Nikko Securities Co., Daiwa Securities Co. and Yamaichi. Officials of Nikko and Daiwa have so far not commented on the reports.