Scholars, writers and members of the public established a chapter in Saitama on Saturday to counter calls to revise the pacifist Constitution.
The body is a local chapter of the Article 9 Association, which was established in June by nine prominent intellectuals to seek a coalition of various political powers and the public to defend the constitutional clause banning the use of military force.
The national group includes Kenzaburo Oe, the 1994 winner of the Nobel Prize for literature.
"We have decided to join hands, beyond differences in beliefs of each of us, to achieve only one common purpose, to defend Article 9," one of the members of the Saitama association said.
Article 9 stipulates, "The Japanese people forever renounce war as a sovereign right of the nation and the threat or use of force as means of settling international disputes."
The founding members of the new group, called Article 9 Association, Saitama, include Tetsuya Takahashi, a professor at the University of Tokyo, and Akira Uozumi, a freelance journalist.
Several local groups, including the one in Saitama, have joined the movement.
The national association said in its inaugural appeal that growing attempts to revise the Constitution "intend for Japan to follow the United States and change into a 'war-waging country.' "
"In order to join hands with all peace-seeking citizens of the globe, we feel that we must strive to shine the light of Article 9 upon this turbulent world. To that end, each and every citizen, as sovereign members of this country, needs to personally adopt the Japanese Constitution, with its Article 9, and reaffirm their belief in it through their daily actions," it said.
The national association said it aims to establish a network to link the local groups to seek further public support for Article 9.