The Democratic Party has demanded Prime Minister Shinzo Abe retract his proposal for amending the Constitution, claiming he has intervened in a process that should be left to the Diet.
The war-renouncing charter has never been amended since its promulgation in 1947.
On Thursday, during the Constitution Commission's first meeting since Abe made the proposal, former disaster management minister Masaharu Nakagawa said Abe had overstepped his authority.