TOKYO, Japan: Takeshi Niinami, chief executive of Japanese beverage giant Suntory, has resigned amid a police investigation into his alleged possession of an illegal drug.

Suntory Holdings President Nobuhiro Torii, a member of the founding family, confirmed the resignation late last week, saying the company had accepted Niinami's decision. He declined to provide specifics on the substance involved, noting that the case remains under investigation.

Niinami, 66, has been a prominent figure in Japan's business community. He is widely credited with driving Suntory's strong growth since becoming CEO in 2014. Under his leadership, profits and sales rose significantly, and he played a leading role in industry lobbying efforts with the government.

"He was a dynamic and decisive leader whom I respect greatly. During his decade at the helm, both profits and sales grew dynamically," Torii told reporters.

Torii did not name a successor but said he would assume full responsibility for the company's operations, including its global business, as he had already been sharing leadership duties with Niinami.

Torii praised Niinami's contributions but said the resignation was unavoidable due to "governance issues." Vice President Kenji Yamada added: "Regardless of the outcome of the investigation, we feel he is not fit for the job."

Both Torii and Yamada suggested the alleged drug could have been a supplement Niinami purchased privately, quoting him as saying he did not know it was illegal. They confirmed police began their investigation last month but declined to give further details.

In Japan, it is customary for executives to step down if their actions embarrass their company. This reflects cultural norms that emphasize accountability and the avoidance of shame.

Suntory, founded in 1899 and renowned for its whisky, beer, soft drinks, and supplements, announced the resignation after markets closed. Its Tokyo-listed shares rose 2.9 percent on September 2.