A manga about an Assassin who has a normal life and a princess is not happy beca

A manga about an Assassin who has a normal life and a princess is not happy because being her obligation to be a princess is unhappy but one day the princess moves away from her family and decides to pick up her crown because it had fallen and was rolling down a dark alley inside the alley was a sleeping demon until the princess lifted her crown the demon had woken up and raising her wings the princess noticed the demon and screamed but the demon took her flying meanwhile the Assassin was shopping and when he was leaving he heard a scream coming from above and saw that the demon was taking the princess so the Assassin threw his katana and stuck it in the demon making the princess fall but before she fell he grabbed her and the princess fell into his hands after the princess thanked them and elegant Assassin took his katana from the body of the demon who was already dead and when the princess was saying goodbye a police car sounded behind her and when she looked back the Plain Assassin was then she returned to her castle and met one of her mothers worried after that her stepmother hugs her and told the King to find her a bodyguard so that nothing bad happens to her and the King agreed while on the other hand the Assassin was at home preparing to go on a new mission until they gave him that the next mission was that he had to deliver Princess Akira so he accepted the proposal but he had to be a little more unrecognized because everyone else had heard that near the city and an Assassin could kill whenever he wants so the Assassin dyes his white hair brown and covers his green eyes with brown contact lenses and infiltrates the castle as a bodyguard and the king chooses him to be the bodyguard so there is no problem says the Assassin and then when the princess arrives at the castle he recognizes her but she does not p