TOKYO (Kyodo) -- A Japanese court on Monday sentenced a man to life in prison for his role in a robbery that led to the death of a 90-year-old woman in western Tokyo in 2023, part of a series of burglaries orchestrated by a man using the pseudonym "Luffy."

In handing down the ruling at the Tachikawa branch of the Tokyo District Court, Presiding Judge Takehiko Okada said Shingo Kato, 26, played "a proactive role based on his strong financial desire and is deeply responsible for the woman's death."

The judge noted that Kato transported the woman, who was tied up, to the basement of her house, where another perpetrator armed with a crossbar was waiting, and said the defendant could have easily foreseen that she would be in grave danger.

Since 2021, a series of robberies and thefts have been reported across the country and at least 50 of them are suspected to be linked to a group led by "Luffy." However, this case was the only one that resulted in a death, shocking the public in Japan, where such violent crimes are rare.

The sentence aligned with the prosecutors' demand. Kato's defense team had sought a fixed prison term, arguing that he was merely following instructions from Rikuto Nagata, another perpetrator in the case.

Nagata, 23, was sentenced to life in prison by the court in November for his key role in the case. He has since appealed the decision.

During the trial, Kato had admitted to the charges, including the robbery resulting in death.

According to the ruling, Kato conspired with others, including Nagata, to enter the woman's home in Komae on Jan. 19, 2023, by posing as a parcel delivery worker. The woman was then kicked and fatally beaten with a crossbar, and items such as watches were stolen from her home.

The defendant was also involved in other crimes, including a burglary in Hiroshima in 2022, it said.

In relation to the series of burglaries, Kiyoto Imamura, 40, known as "Luffy," and three other ringleaders were arrested and indicted in Japan after being deported from the Philippines.

While the ringleaders planned and directed the crimes, the break-ins were carried out by individuals recruited through social media with promises of lucrative "yami baito," meaning dark part-time work in Japanese.