A 25-year-old woman married to a wealthy man who described himself as the "Don Juan" of his locality in western Japan was arrested Wednesday for allegedly killing him three years ago, police said.

Saki Sudo is suspected of causing Kosuke Nozaki, 77, president of a liquor sales company and real estate business, to ingest a lethal amount of an illegal stimulant drug in May 2018 only three months into their marriage, with the deliberate intent to kill him, the police said.

The police arrested Sudo at her home in Tokyo's Shinagawa Ward and transferred her to Wakayama Prefecture where the incident took place. The police declined to disclose whether Sudo has admitted to the allegations.

Photo taken June 4, 2018, shows autobiographies by Kosuke Nozaki titled ""Don Juan of Kishu." (Kyodo)

Nozaki's suspicious death attracted attention as he had gained notoriety for publishing an autobiography titled "Don Juan of Kishu: The Man Who Gave 3 Billion Yen to 4,000 Beautiful Women" in 2016, likening himself to the mythical Spanish playboy.

Kishu is the name of the area in Wakayama Prefecture where he lived. Three billion yen is worth around $27.6 million.

Nozaki was found dead at his home in Tanabe in Wakayama on the evening of May 24 in 2018, with traces of the stimulant drug found in his system but no needle marks on his body, prompting police to investigate the case as a possible poisoning murder.

Before his death, Sudo was alone with Nozaki having dinner with him, the police said.

Suicide has been ruled out, they said, noting Nozaki had planned to attend a funeral for his dog.

According to investigative sources, Sudo had researched about stimulants on the internet and is believed to have obtained the drug found in Nozaki's body.

The Tanabe city government said earlier that it has confirmed that Nozaki said in his will that he would donate all of his property worth around 1.3 billion yen to the city.

But as his legal heir, Sudo was entitled to a portion of his assets despite the will, with the amount to be determined in a legal process.

His relatives, meanwhile, filed a lawsuit last year seeking nullification of the will, claiming someone other than Nozaki had made it.

The house of Kosuke Nozaki, dubbed "Don Juan," in Tanabe, Wakayama Prefecture, is pictured on April 28, 2021. (Kyodo)

Before his death, Nozaki had been embroiled in a series of scandals. In February 2016, his then girlfriend in her 20s, who described herself as a model, was arrested for allegedly stealing cash and jewelry worth 60 million yen from Nozaki's house.

In a later autobiography he published in 2018, Nozaki recalled first meeting a woman believed to be Sudo when she helped him following a fall at Tokyo's Haneda airport the previous year.

After marrying Nozaki, Sudo, who is from Sapporo in Japan's northernmost main island of Hokkaido, had told her family members she was helping a friend's real estate business, but did not initially tell them she had tied the knot, according to her mother.

She has frequently posted photos of overseas trips including to destinations such as Singapore and Bali in Indonesia on social networking sites and told people around her in hometown that she made money through stock trading, according to an acquaintance.

A former classmate from high school said Sudo never mentioned having a job but boasted about her expensive clothes and said she had plenty of money.

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