A few minutes later, as she waited at the railway station another man spat on her. The next day, a Korean school in Tokyo received anonymous phone calls from a man who threatened to kidnap a pupil, strip her and dump her on a river bank.
Dozens more threatening calls were made over the next few days - razor blades were sent through the post, and Korean schools in Japan went into a panic after someone rang the General Association of Korean Residents claiming to have put cyanide in a school water tank.
For the past two and half months Korean Japanese have been taunted, shoved, spat on, threatened, stabbed and even murdered. The majority of the victims have been young girls, travelling to and from school in traditional Korean dress.
There are about 650,000 ethnic Koreans living in Japan and since the early part of the century they have suffered prejudice and occasional violence. This month a United Nations human rights panel listed discrimination against Koreans as one of 30 areas of concern in Japan. But things have rarely been as bad as they are now.
"People feel fearful and scared, but also very angry," said So Chung On, of the General Association, known in Japan as Chosen Soren. "When the situation on the Korean peninsula is tense, when Japan propagates hostility against North Korea, people act on these false allegations, and they victimise people who cannot resist. They aim at schoolchildren, schoolgirls who cannot resist. It is very nasty."
The latest wave of attacks has a very particular cause - the launch by North Korea of a long-range rocket through the skies high above northern Japan on 31 August. It was initially identified by the American military as a ballistic missile; Pyongyang insisted that it was a civilian rocket bearing a small satellite into orbit. Either way, it was a shock to the Japanese who knew nothing of the rocket's existence until after it had plunged into the sea. Sanctions were imposed and the next day, the attacks on the schoolgirls began.
There were 33 separate incidents in September. Last week, petrol bombs were thrown into the Tokyo and Yokohama offices of Chosen Soren. A month ago an official on night duty in the Chiba city branch died after being beaten, strangled, stabbed, soaked in petrol and set alight. The police at first appeared reluctant to acknowledge a political motivation, insisting the killing was part of a botched burglary.
There have been no arrests, although most believe the culprits are members of Japanese right-wing organisations, who regularly parade through the streets, waving Rising Sun flags and blaring martial music.
Leaders of the Chosen Soren are senior members of the Workers' Party and, as the de facto North Korean embassy in Tokyo, it is also believed to channel money from Korean businessmen in Japan to the government in Pyongyang.
In 1994, there were similar attacks during the nuclear crisis when Pyongyang was suspected of developing nuclear weapons. Then, as now, the victims were schoolgirls whose uniform consists of the Korean national costume, a skirt and short jacket called chima chogori. "Even if we don't know whether North Korea launched a missile or a satellite, it should take responsibility for causing anxiety," said Kim Yong, a Korean mother. "But what did Korean schools do? What does it have to do with young children?"