Sparkling firework, which is a Japanese sparker called Senko-hanabi, is composed of black powder containing no metal wrapped in a twisted paper. The firework has a unique beauty with streaks of light similar to the pine needles. For over 300 years, however, physics behind the beauty of the firework is hidden mystery. In this study, detailed high-speed visualization measurements are conducted to quantify the individual stages in the life of sparkling firework. It is confirmed that the droplets, which will be the streaks of light, are formed from liquid atomization induced by bursting of the fireball itself or the bubbles on the surface. The rupture process of non-evaporative droplets is successfully captured, and it is determined that the bursting of a droplet is caused by microexplosion, which is the sudden expansion of gas produced inside the droplet.