Photo/Illutration Takichi Nishiyama in Kita-Kyushu, Fukuoka Prefecture, in September 2022 (Asahi Shimbun file photo)

Journalist Takichi Nishiyama, known for his major scoop involving the secret Japan-U.S. deal over Okinawa's reversion to Japanese sovereignty in 1972, died on Feb. 24. He was 91.

The former political reporter at The Mainichi Shimbun died following heart failure at a care home in Kita-Kyushu, Fukuoka Prefecture.

In 1971, Nishiyama revealed a document indicating the existence of the secret agreement, under which Tokyo agreed to shoulder $4 million to pay for land leveling and other costs required for properties to be returned to Japan from the U.S. military.

Nishiyama made more headlines by the way he had obtained the classified information. 

He approached a female Foreign Ministry official to gain access to classified documents by taking advantage of the intimate relationship he had developed with her.

The pair were arrested in 1972 for leaking the documents and the Supreme Court found him guilty in 1978. He left the Mainichi in 1974 amid the scandal.

Although the Japanese government had long denied it made the deal with Washington, a statement of a former senior Japanese diplomat and documents from U.S. archives have confirmed its existence since 2000.

The Supreme Court rejected Nishiyama’s 2009 lawsuit for the disclosure of the agreement.

Nishiyama's reporting inspired the late best-selling author Toyoko Yamasaki to write a novel based on his life.