The castle was first built by Nagao Kageharu around 1476 and was further fortified and renovated by Hojo Ujikuni when he became lord of the castle under his father Hojo Ujiyasu in 1560. The site of Hachigata Castle is one of the most ideal castle sites in all the Tokyo-Kanto area. It sits at the crossroads for much traffic coming from areas to the North (Shinshu and Joshu) and is nestled between two rivers (Ara River and Fukazawa River) with high cliffs on the Ara River side. Look at the photo of a map in the last picture to see this. These natural defenses along with the vast size of the castle made it a formidable defense for anyone attempting to attack the Hojo from this area.

In 1569 Hachigata Castle turned back the forces of Takeda Shingen, who was forced to go farther South. Then in 1590 when Toyotomi Hideyoshi made his final push towards Odawara to conquer the Hojo, Hachigata castle held off the combined armies of Maeda Toshiie and Uesugi Kagekatsu for a month with 3000 defenders. Ujikuni finally gave in and turned over the castle on the condition that the lives of his men were saved. The castle was later dismantled under the Tokugawa.