Hamamatsu is a city located in western Shizuoka Prefecture, Japan. In September 2023, the city had an estimated population of 780,128 in …Hamamatsu is a city located in western Shizuoka Prefecture, Japan. In September 2023, the city had an estimated population of 780,128 in 340,591 households, making it the prefecture's largest city, with a population density of 500/km² over the total urban area of 1,558.06 km².