Tamaki Matsuoka (L), head of the Japan-China Peace Research Organization, talks with survivors of Nanjing Massacre in a ceremony to mourn the Nanjing Massacre victims at the Memorial Hall of the Victims in Nanjing Massacre by Japanese Invaders on the Qingming Festival in Nanjing, capital of east China's Jiangsu Province, April 5, 2015. Japanese troops captured Nanjing, then China's capital, on Dec. 13 of 1937 and started a 40-odd-day slaughter. More than 300,000 Chinese soldiers who had laid down their arms and civilians were murdered, and over 20,000 women were raped. (Xinhua/Han Yuqing)