[2] Hachiōji Castle is located on the top of Mount Fukasawayama, about five kilometers southwest of central of modern center of Hachioji.

Around the mountain, the outer defense line consisted of clay ramparts and dry moats built to utilize the natural contours of the slope.

[5] While the Hachiōji Castle was still being constructed, the Takeda clan was destroyed in 1582 by an alliance between Oda Nobunaga and Tokugawa Ieyasu, both of whom were also hostile to the Hōjō.

Hōjō Ujiteru left only 1,300 men behind at Hachiōji Castle when he marched in an unsuccessful attempt lift the Siege of Odawara.

Hideyoshi sent a detached force consisted 30,000 soldiers led by Maeda Toshiie, and Uesugi Kagekatsu through Usui Pass.

In early morning of June 23, Toyotomi army of 15,000 men attacked, and Hachiōji Castle was captured before the end of the day.

In 2004, the Ken-Ō Expressway was constructed with a tunnel running directly under the western end of the mountain on which the castle is located.