The White Cat's Revenge as Plotted from the Dragon King's Lap: Volume 8

Despite the casualties along the way, matters in the Imperial Nation have been resolved, and Ruri Morikawa continues to lead a peaceful life with her partner, Jade, in the Nation of the Dragon King. However, things suddenly change when she receives a letter from her grandfather, Beryl, who has been journeying around the other world. The information contained in those letters puts them on high alert. Soon after, they receive a plea for help from the Nation of the Beast King’s Beloved, Celestine, and queen, Padparadscha, learning that the Nation of the Beast King has already fallen into enemy hands! They are informed that they must act fast or the Beast King and everyone else in the country will be in mortal danger. To deal with this unexpected situation, Ruri heads for the Nation of the Beast King...alone?!

[From J-Novel Club]