The girl who saved the world from the hero, what does she see in that world?

Their parents were dead, and she lived with her older sister, but her sister was ordered to serve at the court by the Emperor, a hero who defeated the Demon King. One month later, what returned was her sister's corpse, battered and broken. Leria swears revenge on the hero. And so she trains in a phantom space. In this magical space, time is stretched to one ten-millionth of its normal speed. In other words, while one day passes in the real world, ten million days pass in that world. In the midst of time that threatens to drive her mad, she masters illusory magic and acquires false magic—a magic that writes lies into the world. It bends the laws of reality as far as her magical power allows, enabling her to use all magic and power. It is magic that can even kill gods. The girl's tale of revenge begins. Since this is written according to the author's personal tastes, opinions will likely differ.