With revising the pacifist Constitution rapidly emerging as the primary issue in the upcoming Upper House election, proponents and opponents of change alike used Friday — Constitution Day — to press their cases.

A group in favor of changing the Constitution held a major rally in Tokyo while thousands of its defenders held a protest march through the capital.

In the 66 years since its promulgation, the constitutional debate has rarely been this vigorous. The debate heated up after the Liberal Democratic Party took back control of the government in December, with Prime Minister Shinzo Abe looking to make it a focus of the Upper House campaign this summer.