As a child, Yul opened the door to the village shrine, which was taboo, with the village children, and the monster that came out of the door killed the village children and disappeared, and Yul was driven out of the village. Years later, Yul returned to the village and faced the monster again, and Ji-Soo, the son of the village shaman, told Yul that only the person who opened the door to the shrine can close it again... (Source: Naver, translated)