The behind-the-scenes tales of hit products and creations from Japan: this is Japan's Top Inventions. This time, glow in the dark pigments, which absorb light to glow in the dark. A version of these pigments that contain no radioactive substances was invented in Japan in 1993. They're now used worldwide in products like watch faces and emergency signage. We learn the little-known story behind the pigments' creation, including how they were born from a company in danger of closing down.