The first anniversary was marked Friday of the weekly antinuclear demonstrations in front of the prime minister's office that have grown steadily partly via the popularity of social media.

At the latest rally, the 48th organized by the Metropolitan Coalition Against Nukes, demonstrators chanted "Get rid of nuclear power plants" and "Don't restart them."

According to the organizer, people have taken to the streets in Tokyo's Nagata-cho political district every Friday from 6 p.m. since March 29, 2012, to call for the elimination of nuclear power in light of the Fukushima atomic plant crisis that started on March 11, 2011.

The demonstrations originally attracted around 300 people but grew drastically as word spread through social media networks, including Twitter and Facebook.

Within three months, the weekly rallies started to draw more than 100,000 participants as the then-ruling Democratic Party of Japan moved to restart two reactors at Kansai Electric Power Co.'s Oi nuclear plant in Fukui Prefecture.

Since late last year, several thousand people have been turning out for the rallies.

Misao Redwolf, who played a key role in organizing the rallies, said, "It is very unpleasant to mark the first anniversary, but we have to do it (the rally) as not all reactors have stopped operation yet.

"We believe it is important to continue providing a space where anyone can join in" to protest, she said, adding that antinuclear demonstrations have been held in many places across Japan at the same time each week.

Makio Tahara, 65, who attended the rally with his 10-year-old grandchild, said, "It is hard to achieve a withdrawal from nuclear power acting as an individual, but whether it is effective or not, it is important to express our feelings."