More than a quarter of Japan’s population is over 65 and the country has the highest rate of centenarians in the world. It’s a ticking demographic time bomb as the cost of caring for the elderly rises. But can the solution to this growing problem be found in Kashiwa City near Tokyo? A project there has been looking at how to redesign towns and cities to adapt to their residents as they reach old age. World Hacks asks whether the answers they have found could help ageing populations across the world. Producer: Harriet Noble (for BBC World Service)