After her father—the emperor—was assassinated, Regina became the regent in place of her little brother who was still young.
No matter how well she dealt with domestic affairs, the empire’s vaults emptied out due to how much of a sucker her little bother—the Trash Prince—was. On top of that, there was news that her fiancé was cheating on her…
In the end, she lost everything due to her fiancé leading an insurrection.
However, in her final moments, Regina turned back time with the first emperor’s memento and vowed to become an even bigger trash than her little brother to prevent the errors of her past.