The opening swordfight gives the impression that "Ruler: Master of the Mask" has decided to be an action swashbuckler about Prince Seon fighting for justice against a corrupt regime. Instead, we get a story arc about international trade with Japan. When I saw that Prince Seon had a whole gang of confederates I was sure he was going to, I don't know, steal the tax money or something. But no, he just approaches Hwa-goon to ask for a loan.
That's what Hwa-goon has been up to the last five years. She's a merchant now. It's unclear whether she still works with Dae-mok. My guess is not, because her idea to become the Queen is a lot more viable now that Prince Seon has been replaced by a compliant puppet. Mostly. The other Seon has a brief angry scene where he gets morally indignant about legislation that hits a little close to home.