First thing First the title said it clearly with Empress Word means The MC is actually a female,
Then later in chapter 5 explain why she is being called a eunuch Because there were 2 people that look much a like So her subordinate Kills The eunuch Man and Substitute her to cover things up
So she is actually Acting the eunuch man plot as to get revenge while hiding the fact that she is still Alive after given a sec chance