The cheap diamond company operated by Nezumi-Otoko is a huge success. Kitarō grows suspicious of him, which makes Nezumi-Otoko react sharply, declaring an end to their friendship. The truth is, he was partnering up with Wanyūdō. Nezumi-Otoko brings humans to Wanyūdō's cave, where the yōkai turns them into diamonds and feasts on their souls. He sells these diamonds and becomes a rich trailblazer. One day, A man of a diamond syndicate who has been robbed of business appears and takes Nezumi-Otoko away...!