The book "Unlimited Exchange in the Primordial World" was very similar to the "Dragon Ring of the Nine Underworlds". They both had an exchange system that could be used to exchange for anything. The only difference was that "Unlimited Exchange in the Primordial World" was set in the Primordial World, while the "Dragon Ring of the Nine Underworlds" used a ring as an exchange tool. Both books had many mysterious treasures and magical elements. I believe that readers who like the Dragon Ring of the Nine Underworlds will also be interested in the Unlimited Exchange of the Primordial World. I hope you like this fairy's recommendation. Muah ~😗