Nagano Prefecture, where Spring Drive watches are manufactured, is home to a number of mountains rising over 3,000 meters. The countless rivers that flow from these mountains have, over many years, created a lush, natural environment. The Atera River carves out a deep ravine called the Atera Valley, known for its breathtaking beauty. Using the clear, emerald-green waters of the Atera River as a motif, the dial conjures the image of a stream so clear that one can see the bottom, as well as the rich, natural harmony of summertime. At the heart of this watch is the Spring Drive 5 Days Caliber 9RA2. This movement provides up to 120 hours (5 days) of power when fully wound, as well as an average accuracy of ±10 seconds per month, an astounding achievement for a watch powered by a mainspring.