In the Western world, 2 September is marked as the end of World War II, but in Japan 15 August is observed as the Memorial Day for the end of the war. It is on this day in 1945 when the Emperor accepted the defeat and announced the surrender to the people in Japan on the radio. This broadcast is called 玉音放送（ぎょくおんほうそう）and for most people, that was the first time they ever heard the actual voice of the Emperor.
It is a total coincidence but 15 August is right in the middle of the Buddhism tradition “bon” period (13 Aug to 16 Aug) when Japanese have always remembered departed loved ones and many people have time off work. Lots of events are held on the day in memory of those who had lost their lives in the war.
The official name for 終戦記念日 is 戦没者（せんぼつしゃ）を追悼（ついとう）し平和（へいわ）を祈念（きねん）する日（ひ）, “the day to remember the fallen and to pray for peace.” 73 years on, Japan has changed a lot. The whole world has changed a lot. Most nations which were involved in the World War II have enjoyed the peace for the last 73 years. I hope we can keep enjoying it forever!