Ultranationalist rallies targeted at residents and businesses in the capital's Koreatown district have cast a dark shadow over the once-thriving area.

Sales at a Korean restaurant in the area, just east of Shin-Okubo Station on the JR Yamanote Line, have already been halved, said owner Kim Doc Ho.

Kim, who came to Japan 29 years ago, saw sales surge at the restaurant after the airing of a popular South Korean TV drama sparked a national craze for all things Korean a decade ago.