Mutsu, Japan offers 8 beaches perfect for sunbathing, surfing, swimming, and more. Mutsu is known for Osorezan, a sacred mountain and one of Japan's three great spiritual sites. The best time to travel to Mutsu, Japan, is in late spring (May), when the average air temperature is around 15°C (59°F) and the water temperature is approximately 10°C (50°F). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!