“We want genpatsu [nuclear power plant] in Tokyo!”
“Japanese nuclear power plants are so safe that we could even build one in Tokyo Bay.”
“Radiation can’t get to you if you’re smiling. It only gets to people who are worried.”
“Fukushima has become famous without doing anything. It beat Hiroshima and Nagasaki."
“It’s safe to drink plutonium."
“We couldn’t build a nuclear power plant if we thought about possible accidents. So, we just suck it up.”
“Even if radiation sterilizes your semen, new semen will be produced. The gene god is watching over your semen."
“The lethal dose of salt is 200 grams, and that of plutonium is 32 grams. Plutonium poisoning is no big deal."
“Radiation is good for your health."
“Citizens shouldn’t be allowed to measure radiation levels.”
These are some of the quotes on the signs carried by some 110 demonstrators in Tokyo on September 25, 2011.  The colorfully clad marchers chanted them cheerfully, insisting that “genpatsu are absolutely necessary for Japan’s economic growth” and that building one in Tokyo, the largest consumer of electricity, would be most efficient.
The organizers called this unusual protest “a thoroughly new style of anti-nuclear demonstration using sarcasm.”  Shoppers on the fashionable streets of Ginza looked puzzled at first, but some grinned knowingly as they figured out the demonstration’s true message.
That was a clever idea: the well-known pro-nuclear quotes from influential experts and politicians are infuriating by themselves and have angered many Japanese. By putting them on protest signs along with photos of the men who provided them, however, the demonstrators turned a series of outrageous public statements into a hilariously effective vehicle for their anti-nuclear protest.
It is important to note that this demonstration took place more than six months after the nuclear disaster in Fukushima. The first post-3.11anti-nuclear mass proteststook place on April 10 in ten locations nationwide, including Tokyo, Sapporo, Toyama, Kamakura, Nagoya, Kyoto, Fukushima, Kumamoto, and Okinawa.  The one held in Koenji, an area in metropolitan Tokyo, drew the largest crowd of all: 15,000 people showed up in response to a call from a recycle-store owner who used his blog and Twitter to disseminate the information. He later said he was surprised by the large turnout. There were raw anger and a sense of urgency among the Koenji demonstrators, most of whom looked young.  Those first demonstrations broke an almost month of stunned silence under which confusion, frustration, and fear had simmered.
It is difficult to imagine a sarcastic demonstration having been effective or having had a receptive audience in those early days of the nuclear disaster. It works now, six months later, because so much has happened since and yet the disaster is still ongoing. There have been a number of mass demonstrations since April 10, and they may have been a factor in former prime minister Kan Naoto’s call for a denuclearized Japan. But the new prime minister is equivocating on the genpatsu issue and, despite waves of anti-nuclear mass demonstrations, notably the 9.29 rally in Tokyo that attracted 60,000 participants, some of whom were traveling from Fukushima, Noda announced to the world that Japan will continue to export nuclear power plants.  Under these circumstances, “a thoroughly new style of anti-nuclear demonstration using sarcasm” proved to be an effective innovation.
There is much to write about post-3.11 anti-nuclear protest in Japan, including the long-standing and tenacious protest against existing or planned nuclear power plants. But here is a brief rundown of the larger demonstrations up to the first week of October, 2011. (Focusing on Tokyo)
The Koenji recycle-store owner and his friends continued their calls for protest with a lot of creativity (a live DJ, live music, a “too noisy marching band,” posters, etc.) :
May 7 -- Shibuya (15,000 people)
June 11 -- as part of the nationwide protest (see below)
August 6 -- TEPCO main office & Ginza
September 11 -- Shinjuku (see below)
April 24 -- “Energy Shift Parade” at Yoyogi Park à Shibuya, Tokyo (organized by Energy Shift, a new group formed after 3.11) 
September 19 -- Sayonara genpatsu 10 million people action (60,000) in Tokyo (called for by Nobel laureate Ōe Kenzaburō, Sawachi Hisae, Kamata Satoshi, Ochiai Keiko, and others ) 
It is interesting to watch the videos and compare the demographics and the tenor of different demonstrations. There has been much diversity in demographics and styles among the many “demonstrations, marches, and parades” nationwide, however the 9.25 demonstration in Tokyo may have been the first to use sarcasm to make a point. Given all these activities and creativity since 3.11, it could be worthwhile project to create a data bank of all the demonstrations and protests taking place in nuclear-stricken Japan. Just as the disaster shows the weaknesses of officialdom and corporate Japan, it also shows the vitality of civil society.
 See here for a video and photos of the demonstration.
 In this video, one can see and hear an explosive unleashing of the young protestors’ anger and energy. Also noteworthy was the fact that it was called by someone not affiliated with established organizing bodies like unions and peace organizations and that the participants joined the demonstration spontaneously, many of them for the first time in their lives, having learned of it through social media.
 Address by H.E. Mr. Yoshihiko Noda, Prime Minister of Japan, at the United Nations High-Level Meeting on Nuclear Safety and Security, September 22, 2011, New York.