The suspicious death of a wealthy but troubled Japanese man dubbed "Don Juan" has brought into focus the personal life of the 77-year-old self-proclaimed womanizer who married a 21-year-old earlier this year.

Kosuke Nozaki, president of a liquor sales company and a real estate business in Tanabe in the western Japan prefecture of Wakayama, also known as the Kishu area, was found collapsed at his home on the evening of May 24 and was later pronounced dead. Traces of illegal narcotics were found in his system but no needle mark was on his body, prompting police to investigate the case as a possible murder.

Nozaki published his first autobiography titled "Don Juan of Kishu: The Man Who Gave 3 Billion Yen to 4,000 Beautiful Women" in December 2016, likening himself to the mythical Spanish playboy, after getting into trouble with a woman over money. Three billion yen is worth around $27 million.

(Nozaki's autobiography series "Don Juan of Kishu") 

According to Gendai Business, an online media managed by Kodansha Ltd., the publisher of the autobiography and its sequel released in April this year, he decided to write the first book after a 27-year-old woman he met at a dating club was arrested in February 2016 for stealing cash and jewelry worth 60 million yen from his home.

The case attracted media attention and made him famous after he said in interviews with media outlets, "To me, 60 million yen is waste paper. The theft gave me a good life experience," the website says.

Although prosecutors dropped charges against her, he experienced a similar theft case in 2017.

Nozaki garnered even more media attention and published the second memoir after he married his current wife, a model 55 years his junior, in February.

Nozaki had been previously married and divorced twice and had no children, with his pet dog, a miniature dachshund named Eve, being his only companion until he tied the knot for the third time, according to the website.

The second memoir revealed how the tycoon met his current wife in the fall of 2017 at Tokyo's Haneda airport. He wrote that he intentionally fell down to make her help him up and asked her out for a meal together at a later date.

"I am sorry for the 99 percent of people who wish for this marriage to fall apart, but I am confident that at least I will be happy," he wrote.

Nozaki's death came at a time when he was inviting his acquaintances to the June funeral of Eve, after the dog died in early May.

Murder suspected in death of rich man dubbed Japanese "Don Juan"

The website says Nozaki came from a poor family and became a rich man on his own after starting to work upon graduation from middle school. He became a successful door-to-door salesman of condoms in his 20s, and used the profits to become a money-lender in Tokyo.

Investigators said his wife and a housekeeper were at his home when he was found collapsed on the sofa in his bedroom. The police have searched locations related to him, suspecting he could have been murdered, and collected urine samples from people related to him.

A male neighbor said Nozaki used to deliver advertisements in Tokyo's Nagatacho area before he succeeded in business and did not have many local friends.

"He was saying positive things recently, like he wants to contribute to the local community. It (his death) is truly regrettable," said a man who had known Nozaki since childhood.

In his first memoir, which has sold more than 50,000 copies, Nozaki said, "When I find a woman of my type, tall and voluptuous, I would tell her 'Happy aura, happy elegant, happy nice body (sic). I want to go out with you and have sex with you...I'll give you 400,000 yen if you agree.'"

"Some people may frown at my sense (of relationships), but this is exactly why I have been working in various occupations and earning money. Everybody has a different dream. I don't feel guilty about anything," he wrote.