The person, who has not been publicly identified, was released on Wednesday and will be returning to Japan, Foreign Minister Toshimitsu Motegi told a political talk show programme on Fuji Television.

The individual had been taken into custody in Iran in June, according to Japanese media.

Iran released the person after deciding the individual's jail term was over, Jiji Press reported, citing unnamed Japanese diplomatic sources.

Motegi said the development came after he made "strong calls" to Iranian Foreign Minister Abbas Araghchi to release the detainees.

He confirmed a second Japanese national remained in detention but did not identify the person.

In January, Iran arrested the Tehran bureau chief of Japanese public broadcaster NHK and sent him to a prison known for holding political inmates, according to media reports.

A Japanese government spokesperson at the time told reporters that a Japanese citizen had been detained on January 20 but declined to give more details.

Motegi declined on Sunday to confirm whether the second individual is the NHK journalist.

"As for the other person, we are staying in touch with the person's family and we are working to secure the person's early release," Motegi said during the Fuji TV programme.