The behind-the-scenes tales of hit products and creations from Japan: this is Japan's Top Inventions. This time, we focus on utility knives whose blades, when they become dull, can be snapped off, revealing fresh blades underneath. These knives were invented in 1956 by a Japanese man who took his inspiration from both a "waste not, want not" philosophy and ... chocolate! We cut into the untold drama behind the creation of this revolutionary product, which changed the way the world thinks about utility knives.