Ja-woon, who was living like a mouse, being persecuted by his relatives. Suddenly, an unknown disease began in the village, and many people lost their lives. The people began to sacrifice the village girls as per the village legend, and Ja-woon was taken as a sacrifice to the Imoogi instead of his cousin's sister due to pressure from his family. Ja-woon trembled in fear and called out the name of the small snake 'Sosa, his only friend from childhood. Then, a mysterious man appeared before his eyes. Ja-woon, who realized that he was the Imoogi in the legend, instead of killing him as a sacrifice, treated him affectionately, and he was reminded of his own small snake, Sosa...