A group from Japan visits three Chinese women in Harbin on Tuesday who raised children abandoned by Japanese families after World War II. Three Japanese visitors had been among those children, but none had been raised by the women. [Photo by Liu Yang/China Daily]

A group from Japan mourned victims of Japan's invasion and occupation of northeastern China before and during World War II and called on their leaders to visit China to apologize for war crimes on Tuesday.

The group of 41 was organized by people abandoned as children in China by Japanese families at the end of the war, and included three of them who had returned to Japan. The visit took place on Qingming Festival, the most important occasion for Chinese to honor the dead.

They visited Unit 731 Museum in Harbin, capital of Heilongjiang province, and mourned the more than 3,000 people tortured and killed there. Unit 731 was the Japanese army's germ warfare division, which engaged in experiments on humans.

"It's horrifying to see some of the items on display. Some of them were beyond what I could bear to see," said Nakajima Yohachi, who helped organize the visit.

More than 4,000 Japanese children were adopted in China after World War II, according to media reports. Most have gone back to Japan.

Nakajima, 75, moved to Heilongjiang in 1942 with his family but was abandoned in 1945. He returned to Japan in 1958.He said he wouldn't have survived if it were not for his Chinese parents.

The left-behind children also met with three of the adoptive mothers and gave them gifts. The children they adopted were not in the group.

"Many Japanese are deceived as the history is either distorted or understated in Japanese textbooks," Nakajima said. "We volunteered to come with our own money. We are all peace lovers. We hope Japanese people will gain more knowledge of history, and we also hope there will be no war anymore.

"I think Japanese Prime Minister Shinzo Abe should come to China to apologize for the atrocities and reflect on history. If he doesn't come, many Japanese like me will feel sorry for that," he added.

Japanese dancer Yasuda Yuka, 34, said the atrocities were beyond her imagination.

"I am angry and sad as there are few records in Japanese textbooks about this history. Many young Japanese don't know history well and many even think it's dangerous to come to China," she said.

Six of those abandoned who still live in China accompanied the group .Gao Fengqin, 74, was adopted after her father was killed in the war when she was 5, but she still couldn't go back to Japan, which does not recognize her identity." I am looking forward to going back to hunt for my roots," she said. "But forever, China is my home."