Japan's Emperor Akihito has delivered his traditional New Year address to tens of thousands of well-wishers who flocked to the Imperial Palace. After nearly three decades in the job, the emperor is set to abdicate on April 30, 2019, citing age and health problems. He will be the first emperor to retire in more than two centuries in the world's oldest imperial family. His eldest son, 57-year-old Crown Prince Naruhito, is set to ascend the Chrysanthemum Throne a day later.