During World War II, an atomic bomb was dropped on the city of Nagasaki. Besides the people killed by the blast itself, others were exposed to its radiation and eventually died of radiation poisoning. Among the residents who died of radiation poisoning was reportedly a grandfather of Sunfire.
- In Earth-1218, Nagasaki was initially an insignificant fishing village. In 1571, it was converted to a port town and became the main gateway for trade between Japan and Portugal, Japan's main trading partner at the time. The Portuguese introduced Roman Catholicism to the city and its area, and started interfering in Japanese politics. This eventually caused a backlash by Japanese political and military authorities. In the 17th century, Japan banned Christianity and started an isolationist foreign policy. In 1634, an artificial island called Dejima was constructed in the bay of Nagasaki for use by foreign traders, ensuring that trade would continue but limiting contact between the traders and locals to a minimum. In 1641, Dejima passed under the control of the Netherlands, which started serving as Japan's new main trading partner. Nagasaki, through Dejima, became the only gateway for foreign goods, foreign books, and foreign cultural influences in an otherwise isolationist Japan. It continued playing this role until the end of the isolationist policy during the 19th century.
- In Earth-1218 during World War II, Nagasaki served as a significant ship-building center, port facility, and industrial center. Its strategic significance to the Japanese war effort made it a target for bombing by the United States of America, Japan's main opponent at the time. A number of bombing attacks caused relatively minor damages but much anxiety to the population. On August 9, 1945, a Boeing B-29 Superfortress dropped a plutonium bomb on Nagasaki, codenamed "Fat Man". It severely damaged the city and killed up to 80,000 people from a total population of 263,000 people. This was the second atomic attack on Japan, following the bombing of Hiroshima. Japan announced its intend to surrender on August 15, 1945 and formally surrendered on September 2, 1945. The latter date is considered the last day of World War II.
- In Earth-1218, only the cities of Hiroshima and Nagasaki have ever been targeted by atomic bombs, both attacks taking place in 1945. Despite near-constant threats of nuclear warfare over the following 70+ years, there have been no actual nuclear attacks since the end of World War II.