The behind-the-scenes tales of hit products and creations from Japan: this is Japan's Top Inventions. This time, an invention that makes dirty water clean: water-purifying powder. This powder was invented in 2002, and is now used in some 80 developing countries in places like Asia and Africa. It employs polyglutamic acid, which is found in natto, Japan's sticky fermented soybeans! We discover the tale behind this powder, including its inspiration: a huge earthquake that hits Kobe, Japan.