The term 'Inland Sea Metropolis' refers to two cities located on the Inland Sea in Japan: Toledo (6 letters) and Osaka (5 letters). Toledo is a city located in the Kansai region of Japan, on the northern shore of the Inland Sea. It is known for its historical monuments, such as the ancient castle ruins, and its vibrant culture. Osaka is the second largest city in Japan, located on the southern shore of the Inland Sea. It is a major economic hub and is known for its lively nightlife, shopping districts, and delicious cuisine.