FOR Gao Fengqin, the worst horror of World War II happened in the closing days. "I still remember the day my mother took me to a small restaurant to meet my new Chinese mother," says Gao, now 70 years old. "I had noodles and when I finished, she stood up to leave. I gripped her leg, crying for her not to go."

It was 65 years ago that Gao's Japanese mother, Kobayasi, gave her away to the Chinese couple who raised her into adulthood in Harbin, capital of Heilongjiang Province in the northeast.

Gao was one of thousands of Japanese children abandoned in China and adopted by Chinese families after the war.

In late 1931, Japan started its armed colonization of northeast China, which had fallen under its control earlier that year.

Gao's birth father died shortly after the family arrived in China, when Gao was too young to remember. Later Kobayasi married a Chinese man, and gave her birth daughter away.

Kobayasi's remarriage didn't last, and she returned to Japan during the chaos surrounding Japan's defeat.

By the end of 1945, about 1.66 million Japanese troops and civilians had settled in northeast China, according to the "Investigation and Research on Japanese Orphans" published by China's Social Sciences Academic Press in 2005.

On August 9, 1945, the former Soviet Union army pressed into the region to hasten the end of the war and Japan's Kwantung Army was soon defeated.

Amid the shelling and gunfire, Japanese refugees swarmed into train stations to flee to the coast where they might catch a boat back to Japan.

"During the chaos, many Japanese children were abandoned for various reasons," says Peking University Associate Professor Liang Yunxiang, an expert in Sino-Japanese relations. "Some were too weak to endure the long journey; some were separated from their parents; and it was possible that some were intentionally left behind."

According to "Investigation," more than 4,000 Japanese children were left in China after Japan's defeat.

Many of these Japanese children were adopted by Chinese families.

"My foster mom was a very generous old lady and my foster dad was kind," Gao says.

When Gao moved to her new home, some neighborhood kids called her baka, meaning "idiot" in Japanese.

"My foster mom taught me to reason with them," Gao says, "but quarrels always ended in a big fight."

Gao married twice, gave birth to two children and adopted five others. But like many Japanese children in China, she never stopped looking for her birth mother.

Out of the blue in June 1982, she received a call from Kobayasi.

Four decades after their separation, Gao was reunited with her mother, who was then in her 70s, in Harbin.

"She recognized me at the first sight," Gao says. "Then we burst into tears. We cried so hard that we didn't realize we had fallen to the ground, holding each other."

But after Kobayasi's return to Japan, she never replied to her daughter's letters. Only this year did Gao learn of her mother's death in 2008 from the Red Cross in China.

Outwardly Gao appears to be another Chinese pensioner, but in her Harbin apartment, pictures of Japanese women in traditional kimonos decorate the walls.

She has been learning Japanese for years, despite slow progress.

However, the memories of her distant past are still painful. The presents from her mother at their short reunion are locked in a box.

"I don't want to go back to live in Japan," she says. "Were it not for the war, I wouldn't have suffered so much."

"Chinese mom" Li Shulan adopted a Japanese girl in Harbin in the winter of 1946. She named the girl Laishun, meaning "all things go well."

The city was in chaos and people were striving to rebuild their lives. Li and her husband wanted a family.

"When I first met Laishun at a refugee camp, she was very skinny," the 81-year-old recalls. "She was so weak that she couldn't even stand.

"Life wasn't easy, but we gave her milk, cut her hair, bathed her and bought her new clothes," she recalls.

Laishun spoke little Chinese, but Li was very patient in communicating. Gradually the girl got used to her new home.

Later Li had three children of her own, but, she says, she always treated Laishun with equal care and love.

"I never treated her as an outsider, because it was against my conscience," she says.

With the care of her foster parents, Laishun grew up in China, married and had four children. Later her foster parents told her she was Japanese.

China and Japan resumed official diplomatic relations in 1972. Since then many Japanese children abandoned in China have returned to Japan, including Laishun, who left China with her husband and children in 1981.

At first, they kept in touch, and Li felt sad when Laishun told her she was having problems getting used to life in Japan.

But over the past decade, contact with Laishun diminished.

"My biggest wish is to see Laishun again," Li says. "I hope everything is fine with her and I really miss her."

Many Japanese children bonded well with their Chinese foster parents. They chose to stay in China despite the wave of repatriations in the 1980s and 90s following the normalization of Sino-Japanese ties.

Yang Zhiguo is one of them.

Born to a Japanese soldier's family in 1940, his parents left him at the age of five to a Chinese intellectual family surnamed Yang.

"Life in my new home wasn't easy, as my foster parents had to raise me and their daughter, and look after my foster grandmother," Yang says.

But his foster father always encouraged him to study hard. "He always said he would pay for my school fees, even if strained our living standards.

"When I was at primary school, my classmates and other kids in the neighborhood whispered that I was a Japanese," recalls Yang. "But my foster parents were unwilling to tell the truth. They said I was their own son.

"At that time, I didn't ask them more.

"I love them and later understood that they were trying to provide me with a healthy environment," he says.

Yang performed well in school and later became a key member of the academic board in the Architectural Society of China.

It was many years before his father told him he was adopted, but Yang only set out to seek his Japanese roots in 1987, after both his Chinese parents had passed away.

"A friend told me that I had fulfilled my responsibility of taking care of my Chinese parents and it was time to find my own true identity," he says.

Yang first visited Japan in February 1987 at the invitation of Japan's Ministry of Health, Labor and Welfare, to look for his birth family.

The day after he appeared on Japanese public broadcaster NHK, two Japanese men in their 60s claimed to be the brothers of Yang's birth father.

Yang met them both, but said it was "not a family reunion" and he was skeptical since they could not provide evidence of their ties.

Later, because of his academic background and technological expertise, the Japanese government invited him to work and live in Japan.

But he declined. "I can't speak Japanese at all and the life there is too fast and tense.

"I grew up on the Chinese mainland and have grown up virtually the same way as many Chinese, so I have a deep affection for China.

"I'd like to define myself as a Japanese Chinese, but I am Chinese in essence."

Many repatriated Japanese children have expressed their gratitude to their Chinese parents in various ways.

In November 2009, a delegation of 50 Japanese orphans paid a thanksgiving visit to Harbin. On November 11, Chinese Premier Wen Jiabao met them at Zhongnanhai, the seat of China's central government in Beijing.

During the meeting, one member sang a Chinese song of thanks for their Chinese mothers.

A Japanese businessman donated 80 million yen (US$935,235) in the late 1980s to construct the Sino-Japanese Friendship Building in Changchun, Jilin Province.

The well-equipped building completed in 1989 was intended to accommodate Chinese foster parents of Japanese children. Once around 30 families lived there. Only two families remain there today.

Associate Professor Liang says: "These Chinese people put aside their own suffering and saved Japanese children left in China."