The Fireworks or "missile shows" are a plot element in killer7. When the world's (supposedly entire) supply of nuclear weapons was decommissioned as part of the international anti-terrorism initiative, they were destroyed by launching every single one into space simultaneously and colliding them with each other, creating bright and colourful explosions viewable worldwide. These explosions subsequently became the symbol of global peace.
"Fireworks" also refers to the United States' missile defence system, which operates by firing a barrage of Pulsars at incoming projectiles. Much of the plot of Sunset is concerned with whether or not the United States will deploy the Fireworks in response to the warheads that have been fired at Japan. Negotiators convene at the KAKU building to determine whether or not the US will intervene, as its post-WWII agreement with Japan stipulates, while the world watches to see what the United States will do. Eventually, Garcian Smith and Christopher Mills witness the Fireworks fly over their heads while they are standing on the overpass, signaling the US's decision to keep Japan alive for the time being.