The beginning of the story is super interesting, and I loved every minute of it.
13 years after the palace coup where the son of the crown prince ran away, 3 guys appeared in a guest house. One of them is the Crown Prince's son, Lee Seol, one is his hidden guard, the Watchman and the other is the mysterious guy who later turns out to be Lee Seol's half-brother.

But I should say, the ending wasn't satisfying, it was a HE but I feel like Kang San and Yoo Ha didn't get the ending they deserve.

I really feel bad for both Kang San and Yoo Ha. In the end, Kang San has to give up his real name and Yu Ha has to live in a fake name. It wasn't the most satisfactory ending. And I don't feel satisfied with Yu Ha becoming the king, because I don't see the leader within him. To this whole taking the throne fiasco his contribution cannot even be compared to how much Kang san and the rest have done. He didn't even create the Mokinhoe anti-monarchy organization, he was just an unpopular transcriber in it and wasn't even leading the others. He has been so laid back in everything, and when he gathered people under the name Lee Seol in Mokinhoe, it was not even his idea, he was going along with the people around him. None of his decision was barely from him. While Kang san tried to gather his own people, create a coup on his own, tried his best to enter the palace and become a royal guard, He did everything in his power to get back the throne while Yu Ha was just walking in the path that other's created for him. This was why it disappointed me when he took the throne in the name of Lee Seol. The only brave thing he did in this entire time was to hold out the royal guards from going after Kang San, dan oh and the others when their identities got exposed in the end. Even then, he was waiting for Kang San to save his sorry ass.
And even at the very end, Kang San has to leave so as not to make himself suspicious, like how can this be a satisfying ending? At least Kang San cud have taken the throne and abdicated it to Yoo Ha legitimately.

Also, I do remember in a previous episode when Dan Oh met that servant of the previous Grand Prince, he told that there was a woman who was pretty close to the Grand Prince, who turn out to be Hwa Ryeong. But then Hwa Ryeong gave birth to the Crown Prince's kid. So does that mean the Crown Prince slept with his brother's woman??!! AND Lee Gyeom and Lee Seol are the same age, so does that mean the crown prince went sleeping around with women and doesn't even know when he got her pregnant and after he finds out, he hides the kid and doesn't give a damn for the outside woman?? Even if it was troubled times like wtf, I'm questioning Lee Seols's dad of all the characters in this story. *facepalm*