Kasumigaura (かすみがうら市, Kasumigaura-shi) is a city located in Ibaraki Prefecture, in the northern Kantō region of Japan. As of September 2015, the city had an estimated population of 41,715 and a population density of 266 persons per km². Its total area was 156.60 square kilometres (60.46 sq mi). The city takes its name from the nearby lake, Lake Kasumigaura. The city has the distinction of having the longest name in Japan (in terms of the number of characters used), together with Ichikikushikino and Tsukubamirai. Much of the city is within the borders of the Suigō-Tsukuba Quasi-National Park.