insidehistory on Instagram: "This is one of the rarest and most technically demanding fireworks ever built in human history. 🔥 🌎 Japan’s legendary yonshakudama is a 900 pound aerial shell that takes six months to create, and only a handful are produced each year. Each one is built by hand using centuries old techniques. Artisans layer paper, black powder, and hundreds of individually crafted stars with absolute precision, because even a tiny imbalance can cause the shell to fail during launch.