Thousands of North Koreans living in Japan have demonstrated against what they say is discrimination following Pyongyang's nuclear test last year.
The ethnic Koreans said their children were being bullied
The protesters rallied in a Tokyo park complaining that their community had been bullied by the police.
Hundreds of police kept them apart from a counter-protest by nationalists.
There are more than 500,000 ethnic Koreans in Japan and bilateral ties have soured since Pyongyang carried out its missile and nuclear tests.
The Korean residents group, Chongryon, said about 7,000 people attended the protest in Hibiya Park, although local media put the figure at about 3,000.
Some demonstrators carried pro-Pyongyang placards or carried posters of the North's leader Kim Jong-Il.
They demanded an end to bullying of Korean schoolchildren and the resumption of ferry services to the North that Tokyo shut after the nuclear test in October.
Chongryon official Nam Sung-U told the crowd: "We Koreans in Japan have gone through such suffering during colonial rule and even after liberation. We have united to survive."
Many of the Koreans in Japan are descended from people brought in as forced labour during the Japanese colonial era early last century.
The governor of Tokyo, Shintaro Ishihara, tried to get the protest banned but the courts rejected his request.
Nationalist counter-demonstrators took up positions along the Koreans' protest route to chant slogans.
One major thorn in ties has been abductees - four years ago North Korea admitted its agents had kidnapped 13 Japanese citizens in the 1970s and 80s.