The castle area, centered on a hilly ridge top, extends approximately 380 meters from east to west and 420 meters from north to south. The castle was built on the largest mountain in Iga. It is also believed that the castle was initially built with stone walls, as evidenced by scattered stones approximately 5 meters high and 12 meters wide below, built in a corner of a large flat area that is believed to be the keep of the castle. It is located on the present-day border of Shimotsuge and Hijikigawa in Iga City.
The Kitabatake clan, a feudal lord of Ise Province, wanted to make Iga Province, which had no Shugo (military governor), into Ise Province. In 1575, Kitabatake Tomonori built Maruyama Castle in Kanbe, which he intended to use as a base to invade Iga Province. However, Oda Nobunaga, who aimed at the unification of Japan, gave his second son Chasenmaru (later Nobukatsu) up for adoption to Kitbatake clan, and in 1575, Oda family take over the role of uniting the Kitabatake clan, effectively taking over the Kitabatake family. In the following year, Oda hunted down and killed himself. The construction of Maruyama Castle was also suspended.
In 1578, Oda Nobukatsu set out to repair Maruyama Castle, using Iga as a base. His vassal, Takigawa Saburōbe was in charge of the repairs. In response to this move by the Oda clan, the powerful clans of the Iga province gathered at Mount Tendōzan, across the Kizugawa River from Maruyama Castle, and decided to attack Takigawa.
The all-out attack on Maruyama Castle began at midday on October 25. Takigawa’s forces were defeated and fled that day. This battle was also the beginning of the Tenshō Iga War.
