The prime ward is a core of the castle. It is depicted as “Honjō” (main castle) in the old picture map, and measures 40 m east-west, 27 m north-south. The oldest remain in the castle is a large building (post holes) in about the 14th century that was found in the excavation. Many artifacts were discovered about 1.5 m deep below the ground. Later, the ground was elevated with earth fill as the castle expanded. A part of the earthwork that surrounded the ward remains outside the park,
Nanbatajō Museum, Fujimi City Municipal Museum of History and Folklore