There is little love lost between Takeshi Onaga, the governor of Okinawa, and the Japanese government over the issue of US military facilities in his prefecture. But at least the discussions are largely civil and the law is adhered to.

Not so the unbridled and unregulated accusations on the internet.

Onaga ran in the November 2014 election on a platform of firm opposition to US bases in Okinawa, earning him a landslide victory.

Ever since, he has sought to frustrate efforts by Tokyo and Washington to transfer thousands of US marines and their hardware from Futenma Air Station to Camp Schwab, a base on Okinawa’s northeast coast.

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Onaga and his supporters say the island prefecture bears too much of the burden of US military forces in Japan and the Futenma troops should be moved out of Okinawa entirely.

While discussions between the prefecture and national government drag on and appear to be heading to the Supreme Court, the sniping and the slandering of Onaga and others who support his campaign has become increasingly vicious.

The first attacks on the governor’s personal life can be traced to before the 2014 election, in a series of Twitter messages.

One claimed Onaga’s daughter was married to a senior member of the Chinese Communist Party. Inevitably, the tweet was picked up by like-minded social media users and repeated.

Around the same time, the Mainichi newspaper reported, a virulently nationalist satellite television station called Japanese Culture Channel Sakura aired a programme in which the presenter claimed Onaga’s other daughter was studying in Beijing.

The programme triggered another bout of online accusations which became increasingly detailed. One wweet claimed Onaga had “sent his daughter to study at Peking University” and she was being “shown favouritism” by the Chinese authorities.

The claims found their way into the mainstream as more high-profile commentators weighed in on the debate, including Toshio Tamogami, former head of Japan’s Air Self-Defence Force and a proud nationalist who was forced to resign in 2008 for an essay in which he denied Japan started the war in the Asia-Pacific region.

In a tweet to his 250,000 followers in April 2015, Tamogami repeated the allegation Onaga’s daughter studied in Beijing.

“After that, she married a Chinese man who works for a governmental organisation in Shanghai,” wrote Tamogami, whose conservative opinions include the claim Japan was dragged into the second world war by Chiang Kai-shek and US president Franklin Roosevelt.

“Apparently, the husband is the son of a Princelings [descendants of prominent senior communist officials] member and a senior official of the Chinese Communist Party. Taking all this into consideration, it is easy to understand why Onaga is against the relocation of the US Marine Corps Air Station Futenma to Henoko.”

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The underlying message was clear: Onaga was an agent of the Chinese Communist Party, intent on fomenting unrest in Okinawa to win the support of Beijing.

Even his denials have had little impact. In a session of the prefectural assembly in October 2015, Onaga said: “My eldest daughter works in Okinawa Prefecture and my youngest daughter studies at a university in Saitama Prefecture. They have never even been to China.”

Makoto Watanabe, an associate professor of communications and media at Hokkaido Bunkyo University, said people “do not have to look too hard to find this sort of rumour on the internet”.

“It is a popular tactic of the right-wing to try to provoke a reaction that can then be used to spread the rumour further on the internet,” Watanabe told the South China Morning Post. “From something quite small, they are able to make the claim that Onaga and others who oppose the bases are connected to the Chinese Communist Party.”

Hiroji Yamashiro, chairman of the Okinawa Peace Movement Centre, is another target of baseless accusations.

“On the internet, I am often criticised as being a puppet of China or a communist sympathiser,” he said.

Watanabe suggested that if a claim is simply repeated enough times, it will become “true” in many people’s minds.

“It worries me the number of my students who only get their news and information from the net and who fail to critically examine what they are told,” he said. “This sort of news has not – so far – been mainstream, but it is clear that it could make that leap quite easily. There are a surprising number of people who believe everything that they see or are told.”

Even Onaga’s tactic of largely ignoring the claims made against him and his family is unlikely to stop the online assertions, however scurrilous.

“It may be best to try to ignore them because replying to the messages only encourages the mainstream media to pick up on them, which is exactly what the bloggers want,” Watanabe said.

Failing to refute them, on the other hand, risks them spreading more insidiously and similarly putting down roots.