Local residents built them as escape facilities during war time because wars broke out frequently, and they functioned as military facilities used to carry out resistance movements or struggled with adjacent villages.
これは戦乱が日常化したため、地域の住民が戦乱発生時の避難施設として設けたもので、時には領主への抵抗運動や近隣集落との抗争時に立て籠もる軍事施設としても機能した。