Tsukuba is a city located in Ibaraki Prefecture, Japan. As of January 1, 2024, the city had an estimated population of 256,526 in 121,001 households and a population density of 900 persons per km2. The percentage of the population aged over 65 was 20.3%. The total area of the city is 283.72 square kilometres (109.54 sq mi). It is known as the location of the Tsukuba Science City , a planned scien…