The suspected "Luffy" mastermind and three others believed to be behind a string of Japan robberies and now in detention in the Philippines appear to be senior members of a fraud group from which 36 members were detained in the country in 2019, an investigative source said Saturday.

Police have requested the transfer of the four men to Japan from Manila, after obtaining arrest warrants on suspicion of theft in relation to the fraud, which targeted elderly people in Japan. The suspects named in the arrest warrants include Yuki Watanabe and Kiyoto Imamura.

The four are believed to be behind a spate of robberies starting last year that used similar tactics to the fraud operation, including offering large payouts to individuals recruited to stage the crimes.

Photo taken on Jan. 26, 2023, shows a Bureau of Immigration warden's facility in Manila. (Kyodo) ==Kyodo

In November 2019, authorities in the Philippines detained 36 Japanese men in connection with the fraud group, which used a hotel in Manila as its base to make calls to targets in Japan.

All of the men were returned to Japan between 2020 and 2021, and arrested on suspicion of theft.

Sources also said Saturday that police suspect another man in Japan also used the name "Luffy" online to organize the robberies.

The possibility of a second "Luffy" emerged after a man charged over an attempted robbery in Iwakuni in western Japan's Yamaguchi Prefecture last November said he met an individual using the name in Tokyo and received instructions on how to commit the crime, the sources said.

The meeting occurred after the four Japanese men including the alleged robberies' ringleader were detained at a Manila immigration facility in 2021. The ringleader is believed to have issued instructions on the break-ins from the facility via an encrypted messaging app.

The sources said the indicted man applied for an illegal part-time job via direct message on Twitter that involved collecting cash from fraud victims.

He was then told to install the Telegram encrypted messaging app on his smartphone and meet "Luffy" at Kumegawa Station on the Seibu Shinjuku Line in Higashimurayama, western Tokyo. The individual he met, who spoke with a Kansai accent and appeared to be in his 30s or 40s, issued simple instructions and handed over some cash.

The man then rented a car in Okayama Prefecture and was the driver in the attempted Iwakuni robbery. He picked up an accomplice on the way and received further instructions via Telegram at the scene.

In the attempted robbery of a home by five men in Iwakuni on Nov. 7, residents were threatened with a box cutter, but the group fled after meeting resistance.

The five were indicted last November on charges including attempted robbery, and three of them have been arrested in connection with an October robbery resulting in injury in Inagi, western Tokyo.

According to Japan's National Police Agency, at least 20 cases of theft and robbery in 14 prefectures have occurred since last year, including the murder-robbery of 90-year-old Kinuyo Oshio at home in the city of Komae in western Tokyo on Jan. 19. Over 30 suspects have been arrested in connection with the crimes.

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Presumed mastermind of Japan burglaries may be in Philippines: source