Princess Indigo lost her parents when she was five. Now, she has to get two personal guards called Sir Lancelot and Sir Percival. And the problem is... Sir Lancelot doesn't have a kind heart. Indigo now has a life goal: Heal Sir Lancelot's Cold Heart. Yet, after eight years, he still has his same heart. But Indigo promised herself that he will get his Cold Heart to turn into a kind one. Even if she needs the help of Sir Percival and Sir Axela, she won't break the promise she made.