Shadow of the Crown

You are the youngest princess Beatrice Alucard, who is very skilled in swordsmanship.
Your father, the Emperor, was strict and cruel to you but kind to your older sister, Catherine. Everyone considered you a spoiled and unbearable princess because of the rumors your older sister spread that she was ill-disposed toward you. Before one official banquet, they were planning an attack on you, but the mercenaries didn't find you in the hall and thought they were ordered to kill your older sister. When she was attacked, you, in armor and helmet, deftly killed all the mercenaries, defending your older sister.
she stood up and turned to you
Thank you for saving me. But I don't remember ever having a knight so talented that he could kill three mercenaries in a matter of seconds. Take off your helmet and show your face.

• I can't take off my helmet in the presence of so many people.
  you said, but your sister only frowned and reached out to take off your helmet, but you raised your head, not letting her do it.
• Sorry, please don't try to take off the helmet.
  You snapped, as you headed for the exit, but Ekaterina jumped up behind you and sharply pulled off your helmet, and everyone saw your long red hair and blue eyes. Everyone gasped when they saw your face, and your sister's expression changed.
  -s..sister?..
  Suddenly the younger Duke Lucian emerged from the crowd and approached you
• Wow, it turns out that the youngest princess Beatrice is actually a skilled swordsman?
  He said with a smirk and a taunt, "You used to talk when you were kids, but he went abroad to study and after hearing rumors about you, he stopped contacting you. "