The following is my head cannon for this game. (Part 3)
To become powerful enough to conquer the world, Catherine struck a bargain with a powerful demon king just before promoting the soldier who saved her to general. The demon king would give Catherine a portion of his vast army of dark knights so that she could have them help her rule the world in exchange for the construction of alters that increased the demon king's power. However, every time Catherine needed more dark, she would have to start her conquest all over again because the demon king would always turn back time to the beginning of Catherine's conquest of the world before giving her the dark knights. The only humans who remember everything that happened before the demon king rewound time were Catherine and her general.
The following is my head cannon for this game. (Part 2)
Upon her return to Touria, Catherine made the soldier who saved her the general of Touria's armies, changed her name to Catherine Von Conqueror, made speaking of what happened to the royal family of Touria at the hands of the Omanans punishable by death, and tasked her new general with conquering the world.
The following is my head cannon for this game. (Part 1)
Catherine the 4th was once a kind and caring girl like the rest of her family. But then Catherine's family was murdered and she was kidnapped by the Omanan army during their attempt at conquering the world. Witnessing the death of her family and being held as a prisoner of war by the Omanans for several years twisted Catherine's mind into what it is now. After several years of being held captive, Catherine was single handedly rescued by a Tourian soldier* during the Omanans' fall from power. Catherine developed feelings for her saviour, but she tried to block them out as she didn't want to experience the same pain she felt when she lost everyone she loved years ago, she did accidentally let hints of her love for her hero slip out every so often however.
*The General