This is a “pretend to be my lover” sort of rom-com, and while there can be various issues with this premise, I like this one because it makes sense and it is well executed.
The king tells his son, Prince Leonardo, that he needs to choose a bride within a week, because evidently Leonardo has been dragging his feet on the subject. Right from the start, we can get the sense that the king has asked many times already and has run out of patience. Thus, the deadline, and thus Leonardo grabbing his bodyguard, Lady Knight Chris. It is a shock to Chris herself, but it makes perfect sense.
As the story unfolds, we see that Chris truly is the one who Leonardo wants to marry, having been in love with her with ten years. They’ve known each for a total of fourteen, ever since they were children. Between the time Leonardo had to spent in a neighboring country as a political hostage and dodging the schemes of his step-mother, the current queen, Chris has been his truest friend and staunchest ally. The whole reason that Chris became a knight in the first place was to become strongest enough to protect him.
And that is what makes the story work.
Chris absolutely loves Leonardo. That is never in question. She wants to protect and support him in any way she can. No, the question, and relationship drama, personal tension etc. is the precise nature of that love and whether she can support him as his princess in addition to being his bodyguard, because she is absolutely still his bodyguard.
It is an interesting wrinkle to the Battle Couple trope. On one hand, Leonardo trusts Chris with his life and has full faith in her abilities, but on the other hand, she is also the woman he loves, and so he also wants to protect her. This frustrates Chris, who points out that it is literally her job to get hurt on his behalf, and it is a job that she loves, because again, she loves him. It is a conflict of goals that is cute and wholesome, also funny, such as when a group of assassins feel like they are witnessing a weird lover’s quarrel.
The cute art is a bonus, and the side-stories as well. I’d like to see more of those.
Trickster Eric Novels gives The Knight Captain is the New Princess-to-Be manga volume 1 an A+