Iyo, Japan offers 1 beach perfect for sunbathing, surfing, swimming, and more. Iyo, Shikoku, Japan, is known for the Iyo Railway, one of the oldest railways in Japan. The best time to travel to Iyo, Japan, is in April when the average air temperature is around 15°C (59°F) and the average water temperature is approximately 16°C (61°F). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!