About 24,000 people braved heavy rain to gather in front of the National Diet Building in Chiyoda Ward on Wednesday evening, filling the sidewalks while waving glow sticks and holding signboards.
The demonstrators chanted slogans such as "you can't create peace through force of arms," sending a clear message against imperialist aggression and in defense of global peace.
The emergency rally, titled "emergency action to protect the peace Constitution," was organized by the "We Want Our Future" volunteer group, which includes researchers and artists, along with the "Kenpo Kyujo o Kowasuna! Jikko Iinkai" (Don't destroy Article 9! executive committee).
Singer Miu Sakamoto joined the protest and took the microphone to declare, "The Constitution is absolutely essential to protect the little happiness in our everyday lives. We mustn't let go of it."
A 25-year-old part-time worker from Musashino, Tokyo, said, "I thought I would regret it if I didn't come today."
In a related development, public opposition to any weakening of Japan's pacifist stance has intensified in recent weeks, with around 8,000 people already gathering at the same location on March 10.
Meanwhile, the Liberal Democratic Party led by Prime Minister Sanae Takaichi, who has pushed for constitutional revisions, secured a landslide victory in the February 8 House of Representatives election, winning 316 seats and surpassing the two-thirds majority needed to initiate amendments.
The large turnout on March 25 underscored the growing anti-war sentiment among the Japanese people in the face of ongoing aggression against Iran.