Seventy-three years ago on this day, the city of Nagasaki was struck by an American atomic bomb. It killed more than 70,000 people in that year alone.
Thousands of people are commemorating the day at an annual ceremony in the city's Peace Park. This year will be the first time a UN Secretary-General will attend.
In the early morning hours, many came out to honor the dead and share their wishes for peace.
A middle-aged man said, "For me, this is a day to think about what peace means."
Another person said, "I hope it will not happen again and I wish for peace."
Another young woman said, "We can only imagine what war is like but I heard it was really terrible and I hope it never happens again."
A male survivor in his 70s said, "We have the challenge of how to pass on our experiences to the next generation to tell them how awful the atomic bombing and nuclear war was."
Thursday's ceremony will be attended by representatives from a record 79 countries.
Participants will observe a moment of silence at 11:02 AM -- the exact moment the bomb was dropped.
The names of 3,511 survivors who died in the past year will be added to the list of victims and placed in the cenotaph.