“Our house was damaged and I was very worried about my two sons, who were at primary school at the time, so I went to the police,” she said.

The Korean community reported numerous incidents, such as girls attending Korean high schools having their distinctive Korean-style uniforms slashed by assailants and receiving countless online threats.

There was also an upsurge in political movements such as the ultranationalist Zaitokukai, or the Association of Citizens against the Special Privileges of Second-Generation Koreans, which openly described ethnic Koreans as criminals and “cockroaches”.

Under attack

In January last year, the local government in Kawasaki city, on the southern border of Tokyo, had to boost security at a community centre in one of its primarily Korean neighbourhoods after it received a card threatening to “exterminate” Koreans living in Japan.

The card was delivered a month after the city became the first in Japan to enact a law against hate speech.

In August, a fire ripped through the Utoro district of Uji city, in Kyoto prefecture, which is similarly home to a large Korean community. Seven homes were destroyed in the district of around 50 Korean families, who are the descendants of people drafted into the area during World War II to construct a military airfield.

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A few days after Arimoto’s arrest and with the suspect still in custody, officials of Mindan reported to police that the windows at their office in Hiraoka city, in Osaka prefecture, had been deliberately smashed.

At a rally of Utoro residents, lawyer Gu Yang-ok told the Mainichi newspaper: “I felt as if my own body had been burned. But what I am afraid of most is that there is no reaction from society.”

Chung has the same fear, as relations between Japan and the two Koreas once again appear to be in a downward spiral.

‘Always been that way’

Kim Myong-chol, 70, an ethnic Korean who has spent his entire life in Japan, agrees that tensions are rising.

“Japanese have a special feeling of superiority over Koreans,” he said. “Many of them have a hatred for Koreans and Korean culture and that is the same attitude that they used to justify their colonial rule over the Korean peninsula in the past,” he said.

“Now, the Japanese need a scapegoat to divert public attention away from all the problems that they have at home, and Koreans are an easy target,” he said. “It has always been that way.”

Both Japan and South Korea have elections in the coming months and candidates and parties in both nations have in the past earned political capital by criticising their neighbour.

South Korea’s decision to unilaterally withdraw from an agreement with compensation signed by the two governments in 2015 and which was understood to draw a final line under the issue of Korean sex slaves – euphemistically known as “comfort women” – forced to work in military wartime brothels was met with incredulity and anger in Japan.

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Tokyo responded – although it continues to deny that its actions were retaliation – by halting exports of chemicals critical to South Korea’s semiconductor industry. Relations have been further soured as a number of South Korean courts have found in favour of plaintiffs seeking compensation for years of forced labour at Japanese conglomerates during the colonial period, an issue that Tokyo insists was settled when the two nations forged diplomatic relations in 1965.

“These things seem to come in waves and the new surge is linked to the elections, particularly in South Korea as criticising Japan is a popular position,” Chung said. “And now we have the North testing missiles as well, so there is plenty for Japan to get angry about.

“We seem to be getting into another downward spiral when what is needed is a brave politician to step forward and say ‘enough is enough’,” she said. “But I look around, and I don’t see anyone stepping up.”