A 59-year-old man believed to be one of the main suspects in a bogus land deal in Tokyo has been arrested, a key development in the investigation into a mass-scale fraud that swindled billions of yen from the country's leading house builder.

Misao Kaminsukasu was arrested Friday after arriving in Japan from the Philippines. Since last month, he had been detained in Manila on suspicion of providing false documents to the Japanese Legal Affairs Bureau on June 1, 2017, according to the Japanese police and the Philippines' Bureau of Immigration.

Kaminsukasu, who has denied the allegations, is believed to be one of the masterminds of a criminal group that swindled Sekisui House Ltd. out of about ¥5.55 billion in a deal to sell a 2,000-sq.-meter plot of land in a top-rated location in Tokyo's Shinagawa Ward, an investigative source said.

Kaminsukasu led negotiations with the company for the land, which was formerly used as the site of an inn, a Japanese investigative source said.

Tokyo police have already arrested 16 people in connection with the case. Kaminsukasu fled to the Philippines a few days before eight of them were arrested last October. He turned himself in at the Japanese Embassy in Manila on Dec. 19 after the Tokyo Metropolitan Police Department placed him on an international wanted list. He was then detained by Philippine immigration authorities.

Sekisui House concluded the land deal on April 24, 2017, and had paid ¥6.3 billion in total by June 1 that year.

But an application to change the ownership was turned down by the Japanese bureau as the documents were found to have been tampered with.

The total recognized by police as having been fraudulently gained has been reduced to about ¥5.55 billion, as the company had received ¥750 million from the same group from a different contract to sell an apartment.