Every autumn in the small town of Katakai in Ojiya City, Niigata Prefecture, pyrotechnic fans gather to witness one of the most awe-inspiring fireworks spectacles on the planet — the legendary Yonshakudama. This imposing firework shell, long celebrated for its immense size and explosive display, is launched each year at the Katakai Fireworks Festival, creating a breathtaking bloom that dominates the night sky. The Yonshakudama, known as the “Four Shaku Ball,” is one of the largest single firework shells in the world. The shell measures approximately 120 cm (4 ft) in diameter and weighs around 420 kg (925 lbs), requiring careful handling and a powerful mortar tube to launch it high above the festival grounds.
Once aloft, the Yonshakudama bursts into an expansive flower-like explosion that can span up to 800 metres (2,625 ft) across, painting the sky with luminous sparks that shimmer against the mountains surrounding Katakai.
The Katakai Matsuri, held over two days in early September around Asahara Shrine, features around 15,000 fireworks, with the Yonshakudama serving as the event’s highlight. The festival draws spectators from across Japan and beyond, all keen to experience this explosive tradition that combines artistry, precision and centuries-old community spirit.
Fireworks at Katakai aren’t merely entertainment — they are deeply rooted in local culture as offerings to the shrine, with individuals and businesses contributing to the spectacle as part of a longstanding tradition. Witnessing the Yonshakudama in action is a powerful reminder of Japan’s vibrant hanabi (fireworks) culture and the remarkable craftsmanship behind creating such massive pyrotechnic art.
