Like many students in Japan, Kim Yang Sun cycles to school each morning. Unlike most, she then changes into a traditional Korean outfit and studies under portraits of the late North Korean leaders Kim Il Sung and Kim Jong Il.

The Korean High School in Kita Ward, Tokyo, looks much like any such Japanese institution with a large clock sitting atop a gray buildings. But inside, all notices are written in Korean and female students and teachers wear the traditional "chima jeogori," a full skirt and short jacket.

On a recent tour of the school, students were taking lessons in math, English and Korean, while one class was watching a Japanese-language documentary about South Korean President Park Geun-hye. The curriculum is largely based on that of Japanese high schools, enabling 40 percent of its graduates to go on to university.