Ryouji lives in the secluded mountain town of Sakai-chou. One day, he received a message on his answering machine not to let anyone into the house no matter who it was. In addition, there was something about the letter on the table, but he couldn’t understand all of it due to the static. He opened the letter anyway and inside was a old sepia-coloured letter, with a strange mark that he recalled seeing at the local abandoned shrine. There was a large stone in the middle and when he approached it, he heard a female voice and he felt a pain in his chest. Returning later due to curiosity, he noticed that the emblem on the stone was glowing. All of a sudden, he was dragged into a dark world and a naked girl Kuon was standing in front of him. She was a spirit that was sealed within the stone hundreds of years ago and she decided to thank him by tearing him to pieces and eating him. Just as suddenly, they were back in the real world and all his injuries were healed. It appeared that he had gained her powers which were within the keystone and so he was thrust into battle to retrieve all the broken shards. What is the other world and the village legend which has been passed down? He set out with Kuon and three other girls to seek the truth.