Hon-maru Genkan (front door of the main enclosure of a castle) was located a step lower than Tenshu-dai (base of keep). Thus, when entering the front door, one would pass through Sen-jo-jiki (literally meaning a thousand tatami mat) of Kake-zukuri (overhang method of construction), which was one of the characteristics of Naegi Castle, and go around to enter the keep from the southeast side. The cobbled front door area is depicted in the illustration. Also, many cobbles were found in the survey conducted before the development of the premises. The current stone pavement was reconstructed using the cobbles found here. There were postholes on the huge rock on the right hand side of the front door, demonstrating that the building ( "居間" area, office for the lord, in the illustration) projected outward from the upper part of the huge rock.