After Deducing It Thousands of Times, I Became a Sickly Princess

A hundred years ago, monsters broke through Tianyun City, the main city of destiny of the human race. Since then, the fate of the human race has plummeted. No one can live beyond a hundred years, geniuses are becoming fewer and fewer, and demon tides are becoming more and more frequent. Everyone said that Tianyun City would never be taken back again. Until a sick princess stood up and said, "I'll go." The Allied Forces of the Seven Nations rallied behind her