Ko Yong Hui is seen in this photo taken when she was in Japan in 1973. (Photo courtesy of the source, image partially modified)

TOKYO -- Photos of North Korean leader Kim Jong Un's mother, Ko Yong Hui, taken when she visited Japan in 1973, have been found.

A figure who interacted with Ko at the time has retained the photos taken when Ko visited Japan from July to September 1973 as a dancer with Pyongyang-based Mansudae Art Troupe. Ko passed away in 2004.

Photos showing Ko when she visited Japan are extremely rare and experts say they are valuable materials.

The Mainichi Shimbun asked Tokyo Dental College professor Masatsugu Hashimoto, who specializes in the so-called superimposing method in which multiple photos are compared to a genuine photo to confirm the identity of the person in the images, to examine the photos

The professor responded that the person in the newly discovered photos is identical to Ko.

Ko was a North Korean resident of Japan who was born in the Tsuruhashi district of Osaka in 1952. She is believed to have moved to North Korea in her childhood. She later gave birth to Kim Jong Un and Kim Yo Jong, who is the North Korean leader's sister and a senior member of the Workers' Party of Korea.

During her visit to Japan, Ko participated in the troupe's performances in Tokyo, Nagoya, Osaka and other areas of the country.

The recently discovered photos of Ko were taken in Japan during her free time between performances. In the photos, Ko is seen dressed in plain clothes and smiling.

The existence of Ko is believed to have been withheld from the general public in North Korea.

Atsuhito Isozaki, a Keio University associate professor who is well versed in North Korean politics, said, "Even in Japan, there are few photos that show Ko. I never saw any photo showing her expressions in her personal life before."