πI recommend the following three time-travel novels to you: "Dark Night Demonic Concubine","Arrogant Concubine: Please Have Respect, Your Highness", and "If You Don't Be an Empress, You Have to Die". They all meet the information requirements you provided. The female lead was an assassin or something similar in her previous life. The plot of becoming the queen after transmigrating is also included. I hope you like this fairy's recommendation. Muah ~π