A Japanese citizen, who was adopted by Chinese people during World War II, mourns for adoptive parents in front of a grave in a cemetery to memorize adoptive Chinese parents in Fangzheng county in Northeast China's Heilongjiang province, July 13, 2015. [Photo/Xinhua]

Maita Akemi recalled days when his adoptive parents saved all their food and necessities for him in times of difficulty.

"My mother died in her 50s and never had time to enjoy her life," Maita Akemi said.

"As survivors and witnesses of history, we have an obligation to tell the young people of today's Japan about that period of their history, to let them understand the pain of war. Let us never allow such tragedy be repeated."

The cemetery is located in Fangzheng County near Harbin, capital city of Heilongjiang.