Ever since last summer, when antinuclear demonstrations materialized in response to the Fukushima nuclear reactor meltdown, there's been an ongoing argument about just how many people show up for these protests. Conventional wisdom says the organizers exaggerate the numbers while the major media underestimate them. The tabloid Nikkan Gendai reports that police make their own estimates of crowd size "for security purposes," but, officially, they don't disclose them. Journalist Yusaku Tanaka told the paper that police start counting at the beginning of a rally but neglect to take into account subsequent crowd swell. Reporters in the police-affiliated press clubs get estimates from anonymous sources and then arrive at an average.
Journalist Takeshi Hirose, who started writing about Japan's nuclear power industry long before the Fukushima accident, listed on his blog the numbers reported by individual media outlets for the June 29 rally outside the prime minister's official residence. The organizers claimed 150,000 people showed up, while the reported police estimate was 17,000. Asahi Shimbun said 150,000-180,000, and TBS 200,000. Veteran journalist Shuntaro Torigoe, who covered the demo for Asahi TV's "Hodo Station," thought there were 40,000-50,000 people. The relatively conservative Sankei Shimbun ventured 20,000 and the relatively liberal Mainichi published both the organizers' and the police's estimates. NHK simply said the number was "higher" than the number that showed up for the previous week's protest. The Yomiuri didn't mention any figures, because it didn't cover it.
Though the numbers varied, everyone except the Yomiuri reported something, and it wasn't necessarily the police estimate, which is why Hirose marks June 29 as the date when the major media's "stance toward coverage of the antinuclear movement" changed. There had been demonstrations in front of the PM's residence every Friday night since March 29, ostensibly to protest the restart of the Oi reactor in Fukui Prefecture, but the mainstream vernacular press had provided almost no coverage. On June 29, according to Hirose, most media, TV news shows in particular, had finally been given "the go-ahead" to cover the demonstrations.