An anti-nuclear group led by Japanese author and Nobel literature laureate Kenzaburo Oe and other celebrities held demonstrations in Tokyo and Niigata Prefecture, Kyodo News reported.
"If we think about the children of tomorrow and to fulfill our ethical responsibilities to future [generations], we must strongly propose the abandonment of all nuclear power plants," Oe said at Tokyo's Yoyogi Park, where organizers said 12,000 protesters gathered.
Oe said "handing nuclear waste generated from the nuclear reactors to our grandchildren" is "unethical conduct.''
The group is seeking to collect 10 million signatures opposing nuclear power in its campaign, "10 Million People's Action to Say Goodbye to Nuclear Power Plants."
It already has collected about 4 million signatures supporting abolition of the nation's 54 commercial reactors, its executive committee said.
The group also plans a rally in Koriyama, Fukushima Prefecture, on the first anniversary of the March 11 disaster in which a magnitude-9 earthquake and tsunami led to a meltdown at the Fukushima nuclear power plant.
The petition drive will continue through March, and the group then plans to submit its petition to Prime Minister Yoshihiko Noda and leaders of both chambers of the Diet.