The new revelations could deal another serious blow to Prime Minister Shinzo Abe, whose administration is already facing a public backlash over its bid to turn Japan's shuttered nuclear reactors back on while his plan to revive the economy stalls.
Today, newly appointed industry minister Yoichi Miyazawa, a Harvard graduate and former senior bureaucrat in the finance ministry, distanced himself from the affair, saying he wasn't present at the sex club in the city of Hiroshima.
"I came to know of that through a media report, and it was true," Miyazawa told reporters in Tokyo.
"It is also true that I myself was not there," he added.
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The venue's shows include women being tied up with ropes and male patrons whipping them, according to blog posts written by club visitors.
It was not immediately clear if Miyazawa - a nephew of late prime minister Kiichi Miyazawa and a cousin of Foreign Minister Fumio Kishida - would step down.
On Tuesday, Miyazawa was tapped to replace industry minister Yuko Obuchi, who stepped down over claims she misspent political funds, while Justice Minister Midori Matsushima also quit after days of allegations that she had misspent money in what opponents insisted was an attempt to buy votes.
The double resignations marked the first significant problem for Abe since he swept to power in December 2012, ending years of fragile governments that swapped prime ministers on an annual basis.
This week's resignations were also a blow to Abe's bid to boost the profile of working women in Japan.
However, Tomoaki Iwai, a political scientist at Nihon University, said Abe would likely survive the latest crisis.
"The spending was inappropriate and embarrassing," and it reflects badly on Miyazawa's supervisory abilities, he said.