Matsumoto, Nagano is 16 times larger than San Marino.
Area: 61 km2 World Factbook
Population: 32,742 (July 2014) World Factbook
San Marino, officially the Republic of San Marino and also known as the Most Serene Republic of San Marino, is an enclaved microstate surrounded by Italy, situated on the Italian Peninsula on the north-eastern side of the Apennine Mountains. Wikipedia
Area: 978 km2 calculated
Matsumoto is a Japanese city in the Chūbu region on the island of Honshu. It is a city located in Nagano Prefecture. Matsumoto is designated as a Special City. As of July 1, 2012, the city has an estimated population of 243,571 and a population density of 250 persons per km². Wikipedia