Moriyama is a city located in Shiga Prefecture, Japan. As of 31 August 2021, the city had an estimated population of 85,485 in 34366 houseā¦Moriyama is a city located in Shiga Prefecture, Japan. As of 31 August 2021, the city had an estimated population of 85,485 in 34366 households and a population density of 1533.63 persons per km². The total area of the city is 55.74 square kilometres.