This sit-in was the first since last month's news that the Treaty on the Prohibition of Nuclear Weapons will come into force in January after it was ratified by the 50th country, the minimum needed to take effect.

Kawano Koichi, who heads Hibakuren, a liaison council of atomic bomb survivors for the Peace Movement Center in Nagasaki Prefecture, said he's happy about the treaty, but he also said he is angry with the Japanese government. He said he wants the government to be in the forefront of efforts to eliminate nuclear weapons.

The United States and other nuclear powers are refusing to ratify the treaty. Japan is under the US nuclear umbrella and the Japanese government has indicated that it will not ratify the treaty, saying that the pact will not to lead to nuclear disarmament.

Kawano also referred to US President-elect Joe Biden. Noting that Biden has said he will follow former President Barack Obama's footsteps, Kawano said he expects the United States, under Biden, to spearhead the effort to eliminate nuclear arms. Kawano added nuclear arms will not disappear immediately, but the world will certainly change.

Another participant at the sit-in, a second-year high school student, said the United States has great influence, and she wants Biden to work aggressively toward a nuclear-free world.