Kosuke Nozaki Japan’s Wealthy “Don Juan” Poisoned to Death in Tanabe Wakayama Japan

Kosuke Nozaki, a self-proclaimed playboy and wealthy businessman, led a life that seemed straight out of a novel. His autobiography, Don Juan of Kishu: The Man Who Gave 3 Billion Yen to 4,000 Beautiful Women, painted him as a wealthy and eccentric real estate mogul who showered women with extravagant gifts. However, his story took a dark and tragic turn when he was found dead under suspicious circumstances in his Tanabe, Wakayama home on May 24, 2018.

His death immediately sparked controversy, given his extravagant lifestyle, his history with women, and the sudden nature of his passing. The official cause was listed as acute poisoning from a stimulant drug, but the circumstances surrounding his death raised numerous questions. Was it a suicide, an accident, or a carefully planned murder?

Who Was Kosuke Nozaki?

Born in 1941, Nozaki built his fortune through real estate, lending, and the liquor industry. His larger-than-life persona and flamboyant lifestyle made him a well-known figure in Japan, particularly in the Wakayama Prefecture. Nozaki often boasted about his wealth and his relationships with women, which he detailed extensively in his book.

Despite his wealth and success, his personal life was complicated. He had been married multiple times and had a reputation for seeking young, beautiful women. His most recent marriage, to 22-year-old Saki Sudo in February 2018, raised eyebrows due to their significant age gap.

The Events Leading to His Death

On the evening of May 24, 2018, Nozaki was found unconscious at his home. His wife, Saki Sudo, reportedly discovered him in a lifeless state and called emergency services. Paramedics arrived, but he was pronounced dead shortly after.

Initial investigations suggested that Nozaki had died from a stimulant overdose. However, police found no signs of needle marks on his body, leading to speculation that the drugs had been ingested rather than injected. Traces of the substance were later found in his stomach during the autopsy.

Suspicion Falls on Saki Sudo

Given the circumstances, investigators turned their attention to Nozaki’s young wife, Saki Sudo. Their marriage had been brief, and reports suggested that Sudo stood to inherit a significant portion of Nozaki’s fortune.

Further scrutiny revealed suspicious activities leading up to Nozaki’s death:

• Internet searches: Authorities found that Sudo had searched for terms such as “perfect crime” and “lethal stimulant dosage” before Nozaki’s death.
• Financial motive: While Nozaki had been known for his generosity, some believed that Sudo may have married him with financial intentions.
• Lack of direct evidence: Despite suspicions, there was no direct proof that Sudo had administered the lethal dose.

In 2021, three years after Nozaki’s death, Sudo was arrested and formally charged with his murder. Prosecutors alleged that she had poisoned him to gain access to his fortune. However, her defense team maintained that there was no concrete evidence linking her to the crime.

Legal Battle and Acquittal

Sudo’s trial began in 2024, drawing significant media attention. The prosecution relied heavily on circumstantial evidence, arguing that Sudo had the means, motive, and opportunity to kill Nozaki. They highlighted:

• The suspicious internet searches.
• Her presence at the house at the time of his death.
• The potential financial gain.

However, the defense countered that:

• There was no direct evidence proving she administered the drugs.
• No surveillance footage or eyewitness testimony placed her as the person who poisoned Nozaki.
• The possibility that Nozaki had taken the drugs himself, whether knowingly or unknowingly, could not be ruled out.

In December 2024, the Wakayama District Court found Sudo not guilty, citing insufficient evidence. Judge Keiko Fukushima stated that while suspicions remained, the burden of proof had not been met to justify a conviction. The court ruled that it was possible Nozaki had ingested the drugs accidentally.

The Aftermath and Public Reaction

The verdict sparked mixed reactions across Japan. Many believed that justice had not been served, while others saw the acquittal as a reflection of the Japanese legal system’s reliance on solid evidence for convictions.

Sudo’s acquittal was especially notable given Japan’s high conviction rate, where over 99% of criminal cases result in guilty verdicts. Her ability to walk free despite the heavy suspicions surrounding her made the case one of the most talked-about legal battles in recent Japanese history.

However, Sudo did not escape legal trouble entirely. At the time of her acquittal, she was already serving a three-year and six-month prison sentence for an unrelated fraud case. She had been convicted of swindling a man out of nearly 30 million yen (approximately $200,000).

Unanswered Questions and Theories

Despite the court’s decision, many questions about Nozaki’s death remain unanswered:

• Did Nozaki take the drugs himself? Some speculate that Nozaki might have been experimenting with stimulants for the first time and accidentally overdosed.
• Could someone else have been involved? While Sudo was the prime suspect, investigators never found conclusive proof that she acted alone—or at all.
• Was there a third party? Given Nozaki’s wealth and controversial lifestyle, some believe that a business rival, former lover, or someone else with a grudge may have played a role.

The lack of definitive answers continues to fuel speculation and conspiracy theories about the case.

Final Thoughts: A Case That Captivated Japan

The death of Kosuke Nozaki remains one of Japan’s most mysterious high-profile cases. His extravagant lifestyle, controversial relationships, and sudden death created a story that captivated the public for years.

Despite Sudo’s acquittal, doubts remain, and the full truth of what happened on May 24, 2018, may never be known. Whether it was a carefully orchestrated crime or an unfortunate accident, Nozaki’s death has left an enduring mark on Japan’s legal and social landscape.