In Edenia, Tanya had located the ancient texts that described the process by which to fuse the Kamidogu into one. With this information, Onaga was able to create the One Kamidogu - a tool of unspeakable power.
As the Dragon King was distracted, reveling in his victory, Tanya seized the opportunity to snatch the Kamidogu from him, thereby obtaining god-like power. She destroyed the Dragon King and became Ultimate Overlord of the realms.
