Members of a Japanese delegation mourn for the victims at the Memorial Hall of the Victims in Nanjing Massacre by Japanese Invaders in Nanjing, capital of east China's Jiangsu province, March 31, 2017. The delegation has visited Nanjing to mourn for the victims by planting trees during the Tomb-sweeping Day holiday, or Qingming for 32 consecutive years since 1986. [Photo/Xinhua]

Members of a Japanese delegation mourn for the victims at the Memorial Hall of the Victims in Nanjing Massacre by Japanese Invaders in Nanjing, capital of east China's Jiangsu province, March 31, 2017. The delegation has visited Nanjing to mourn for the victims by planting trees during the Tomb-sweeping Day holiday, or Qingming for 32 consecutive years since 1986. [Photo/Xinhua]

Members of a Japanese delegation mourn for the victims at the Memorial Hall of the Victims in Nanjing Massacre by Japanese Invaders in Nanjing, capital of east China's Jiangsu province, March 31, 2017. The delegation has visited Nanjing to mourn for the victims by planting trees during the Tomb-sweeping Day holiday, or Qingming for 32 consecutive years since 1986. [Photo/Xinhua]

Members of a Japanese delegation mourn for the victims at the Memorial Hall of the Victims in Nanjing Massacre by Japanese Invaders in Nanjing, capital of east China's Jiangsu province, March 31, 2017. The delegation has visited Nanjing to mourn for the victims by planting trees during the Tomb-sweeping Day holiday, or Qingming for 32 consecutive years since 1986. [Photo/Xinhua]

Members of a Japanese delegation mourn for the victims at the Memorial Hall of the Victims in Nanjing Massacre by Japanese Invaders in Nanjing, capital of east China's Jiangsu province, March 31, 2017. The delegation has visited Nanjing to mourn for the victims by planting trees during the Tomb-sweeping Day holiday, or Qingming for 32 consecutive years since 1986. [Photo/Xinhua]

Members of a Japanese delegation mourn for the victims at the Memorial Hall of the Victims in Nanjing Massacre by Japanese Invaders in Nanjing, capital of east China's Jiangsu province, March 31, 2017. The delegation has visited Nanjing to mourn for the victims by planting trees during the Tomb-sweeping Day holiday, or Qingming for 32 consecutive years since 1986. [Photo/Xinhua]

An old woman touches a monument in the garden of the Memorial Hall of the Victims of Nanjing Massacre by Japanese Invaders in Nanjing, Jiangsu province, March 31, 2017. [Photo/Chinanews.com]

Members of a Japanese delegation mourn for the victims at the Memorial Hall of the Victims in Nanjing Massacre by Japanese Invaders in Nanjing, capital of east China's Jiangsu province, March 31, 2017. The delegation has visited Nanjing to mourn for the victims by planting trees during the Tomb-sweeping Day holiday, or Qingming for 32 consecutive years since 1986. [Photo/Xinhua]