
I don't get the last part, I mean, what does it mean the Kai empire's lord spoke out in the last pages?

If I remember correctly, the slaves and Nadia incidents that were happening in Koka were all Kai empire’s doing. So Yona was like triggering those from Kai by saying that she sunk their boats and that some Kai citizens were under their custody. With that man reacting to all those, it means that he knows about all those incidents and proves that he knows about that slaves and drugs.
I just love that after the awaited confession and the love and all, we're getting three or four chapters of them just having sex