It's sad, but there's a lot of Deliberate Values Dissonance going on with Yotsuyu's story. Brothels, and selling people to work in them isn't illegal in Doma, which is probably a reference to how it was in historical Japan. I really have to wonder how many woman were in Yotsuyu's same situation and didn't end up growing up to be monsters. It's also very obvious that her family was almost as bad as she was. They just didn't have the influence she did. I get the feeling that a lot of what she put the Doman people through were things Yotsuyu learned from her aunt and uncle and brother first. I don't want to say she was too far gone when her aunt and uncle sold her too the brothel, but I get the feeling she would have snapped no matter where she ended up.

The problem with Hian calling attention to Yotsusyu's past is that the way Yotsuyu took her anger out on everyone is very obviously disproportionate to what she went though. Trying to convince an entire nation that the person who tormented them is semi-justified for what they did because the people of the nation, most of who could never have been in a position to do anything about Yotsuyu's situation, let it happen is a really hard sell. I don't see it happening.

The other problem is timing. Doma's infrastructure and culture was decimated by the Imperials. The Domans are going to be spending years rebuilding and reclaiming who they are nation. Inserting the idea that the last Imperial Viceroy was justified in what she did would cause moral to plummet. That's the last thing Doma needs right now.

I can see the truth coming out later, but not when the wounds Yotsuyu gave Doma are so fresh. The important thing is that Hian knows as he's the one in charge of rebuilding Doma. For now, that's enough.