Yonshakudama

The yonshakudama is one of the largest traditional aerial fireworks ever produced, originating in Japan and measuring roughly four shaku (about 120 centimeters) in diameter, with a total weight that can exceed 400 kilograms.

Manufacturing one is an intensive artisanal and engineering process that can take months, requiring a reinforced paper shell built in layered hemispheres, precision-packed bursting charges, and thousands of individually arranged “stars” to ensure a perfectly spherical bloom nearly 800 meters wide in the sky.

The internal chemistry relies on a massive central black-powder bursting charge, while the stars contain carefully balanced mixtures of oxidizers, fuels, binders, and metal salts—such as strontium for red, barium for green, and aluminum or magnesium for brilliance—designed to ignite uniformly despite extreme centrifugal forces.

Because of the materials, labor, testing, and safety controls involved, a single yonshakudama can cost tens of thousands of dollars, and only a handful of Japanese pyrotechnicians are licensed and experienced enough to build and launch them, making each firing a rare, high-risk, and highly celebrated event in Japan’s major firework festivals.