The Working Group on Arbitrary Detention and 3 Special Rapporteurs expressed concern about the arrest and detention of Hiroji Yamashiro, who heads the Okinawa Peace Action Center, in a letter of February 28 to the Japanese authorities.
The Japanese government sent a response to the statement in April.
Following documents became available on May 28.
Joint Urgent Appeal: Mandates of the Working Group on Arbitrary Detention; the Special Rapporteur on the promotion and protection of the right to freedom of opinion and expression; the Special Rapporteur on the rights to freedom of peaceful assembly and of association; and the Special Rapporteur on the situation of human rights defenders (PDF)
Reply of the Government of Japan to the Joint Urgent Appeal from Special Procedures of the United Nations Human Rights Council (PDF)
UN 'concerned' about Japanese activist's detention (May 28, 2017 NHK World)