During the 74th archaeological dig, found were the remains of a large building constructed in the middle of the Yayoi period (2nd century B.C.), the dimensions of which are more than 7 meters in a east-west direction x 11.4 meters in north-south. Sixteen postholes were found and three of them had pillars of zelkova tree. The pillars to support the ridge of a roof were made of a kind of mulberry tree. The building had been a core facility in the western area until the period when the Karako-Kagi Site was surrounded by a large circle moat.