While Cairo was staring at the previous Kingdom of his sister, he etched the destroyed image of it into the deepest part of his memory so that he wouldn't be able to forget it even if he wants to
In the future, when Cairo gained enough strength to the point that he can single-handedly dominate the world, he would make sure that the enemies of him that have even the slightest connection to the bad thing that happened to the Larton Kingdom will have the same ending
Cairo will make sure that not even one of them will be let off. All of them will die with their Kingdoms utterly destroyed to the point that they wouldn't be able to recognize their homes anymore
Cairo's thoughts sounded terribly arrogant but he will make sure to turn it into reality. No one can stop him from achieving what he wants no matter who they are