Japanese police have requested that Philippine authorities hand over four or five Japanese nationals being held at an immigration facility in greater Manila.

At least one of them is thought to be an organizer of a series of robberies across Japan.

The suspects include Watanabe Yuki and Imamura Kiyoto. Tokyo police had obtained arrest warrants for them and others for their alleged involvement in a scam in 2019.

Philippine Justice Secretary Jesus Crispin Remulla told NHK that Japanese police believe Watanabe may have used the alias "Luffy."

He revealed that Watanabe has been detained at the immigration facility since 2021.

Remulla told NHK that he wants to discuss the matter with the Japanese government to find out what it wants to be done.

He confirmed that phones are now banned at the facility so detainees cannot communicate with anyone outside.

Authorities in the Philippines say Imamura can be handed over to Japan as soon as the necessary paperwork has been completed.

They indicated that Watanabe cannot be delivered to Japanese authorities until legal procedures are completed in a case pending against him in the Philippines, but that he could be handed over if the procedures are suspended.

The justice secretary said he wants to examine the case in detail before he decides how to respond to the Japanese government's request.

Police believe a person using the name "Luffy" recruited people to commit a number of robberies in Japan and gave them instructions through social media.

They suspect the group that "Luffy" belongs to was involved in robberies in at least 14 prefectures.

Investigators have not confirmed if the name "Luffy" was used by a single person or multiple people.