Japan said Monday that one of two Japanese nationals detained in Iran has returned home in good health, as Tokyo continued diplomatic efforts for the release of the second person.

The confirmation came from Chief Cabinet Secretary Minoru Kihara, who said at a regular news conference that the former detainee arrived in Japan on Sunday and was in good health, after Foreign Minister Toshimitsu Motegi announced the release the day before.

Motegi made his disclosure Sunday on a Fuji Television talk show, saying the person had been detained since last year and was released on Wednesday. Motegi said the person took a flight from Azerbaijan before returning to Japan.

Kihara said Japan’s second detainee—another Japanese national arrested earlier this year—remained in custody in Iran. He told reporters that Japan has confirmed there is no problem with the person’s safety and health and said Japan is continuing to press Iran for a release as soon as possible.

Motegi said the release followed his repeated demands to Iranian Foreign Minister Abbas Araghchi and that he was working to win an early release of the other detainee. He also said he was communicating with the person’s family and other concerned parties.

The Committee to Protect Journalists has previously said the detainee identified in January is a journalist at Japan’s public broadcaster NHK. CPJ said the NHK reporter was arrested on Jan. 20 by the Islamic Revolutionary Guard Corps and transferred Feb. 23 to Evin Prison, citing unidentified sources that described a fear of persecution.

In a statement earlier this month, Japan’s Foreign Ministry said the detainees were safe and in good health, but it acknowledged only that one was detained last year and the other one detained in January, and it provided no further details. The ministry also did not say whether the two cases were related.