This Empress wants to stay low

After surviving an apocalypse Aluna defeated the evil monster who had plague her universe. She sealed the monster by sacrificing herself and revived everyone. The wandering souls that were killed by the monster decides to give her a second chance at life. She was reborn as the granddaughter of powerful prime minister in a different world. She once thought that she can have a peaceful life and then her ambitious grandfather married her off to the cold blooded emperor. Now she really has to stay low but it seems like her past will haunt her and it even followed her to this new world. Ethan Chen was transmigrated into another world after he was betrayed by his best friend. After many hardships he ended up sitting on the throne. Amongst him, there were still many enemies. Especially Prime Minister Ying BuChu who had always spoken out against him. Before he can balance out the royal court he would have to take out prime minister Ying.