is a city located in the western portion of the Tokyo Metropolis, Japan. , the city has an estimated population of 561,344, and a population density of 3,000 persons per km<sup>2</sup>. The total area of the city is . It is the most populous city in Tokyo outside of the special wards. In 2015, it was designated as a core city for the first time in Tokyo. It was the second city in Tokyo Prefecture (present-day Tokyo) to implement the municipal system after Tokyo City (present-day Tokyo's 23 wards).
Hachià Âji is located in the foothills of the Okutama Mountains of western Tokyo, about 40 kilometers west of the center of the 23 special wards of Tokyo. The city is surrounded on three sides by mountains, forming the Hachioji Basin which opens up toward the east in the direction of Tokyo. The mountain ranges in the southwest include Mount Takao (599 m) and Mount Jinba (857 m), two popular hiking destinations which can be reached by train and bus, respectively.
Hachià Âji has a humid subtropical climate (Köppen Cfa) characterized by warm summers and cool winters with light to no snowfall. The average annual temperature in Hachià Âji is 13.9 ðC. The average annual rainfall is 1998 mm with September as the wettest month. The temperatures are highest on average in August, at around 25.3 ðC, and lowest in January, at around 2.4 ðC.
Per Japanese census data, the population of Hachià Âji has recently plateaued after nine decades of strong growth.
The area of present-day Hachià Âji was part of ancient Musashi Province. It has been an important junction point and post town along the Kà Âshà « Kaidà Â, the main road that connected the historical Edo (today's Tokyo) with western Japan. Hachià Âji Castle was built during the Sengoku period in 1584 by Hà Âjà  Ujiteru, but was destroyed in 1590 by Toyotomi Hideyoshi. During the Edo period, the area was tenryà  controlled directly by the Tokugawa shogunate. In the post-Meiji Restoration cadastral reform of July 22, 1878, the area became part of Minamitama District in Kanagawa Prefecture. The town of Hachià Âji was created on April 1, 1889, with the establishment of the modern municipalities system. Minaitama District was transferred to the administrative control of Tokyo Metropolis on April 1, 1893. Hachià Âji gained city status on September 1, 1917.
During the 1964 Summer Olympics, the city was host to the cycling events. The Hachioji Velodrome was used for the events.
Hachià Âji became a Core city on April 1, 2015, with increased local autonomy.
Hachià Âji has a mayor-council form of government with a directly elected mayor and a unicameral city council of 40 members, whose members are elected for a four-year term. Hachià Âji contributes five members to the Tokyo Metropolitan Assembly. In terms of national politics, the city is divided between the Tokyo 21st district and Tokyo 24th district of the lower house of the Diet of Japan.
During the Meiji period, Hachià Âji prospered as an important location for the production of silk and silk textiles. The industry faded away, however, in the 1960s. Today, Hachià Âji mainly serves as a commuter town for people working in Tokyo, and as a location for many large colleges and universities.
The Tokyo Metropolitan Government Board of Education operates nine public high schools, and the Hachioji School for the Blind. There are also eleven private high schools.
Metropolitan high schools:
Hachià Âji has 70 public elementary schools and 37 public junior high schools operated by the city government, as well as four public combined elementary/junior high schools.
Combined public elementary and junior high schools:
Municipal junior high schools:
Municipal elementary schools:
Former:
JR East - Chà «à  Main Line
Keio Corporation - Keià  Line
Keio Corporation - Keià  Takao Line
Keio Corporation - Sagamihara Line
Tokyo Tama Intercity Monorail - Tama Toshi Monorail Line
Hachioji stretches over a large area, combining such diverse parts as the densely populated city center and its shopping district with the hardly populated rural areas in the west.