No one’s looking close enough. Yuhon’s lie was him knowing if Kashi was a priestess. Il jumped to the conclusion that Yuhon killed Kashi on his own. Does no one realize the whole purpose of being shown this backstory? For nearly two hundred chapters, we’ve thought Yuhon had killed Kashi since day one. Before this, all we’ve known of Yuhon was that he was respected by the people of Kouka, but a cold blooded killer to all. The whole point of this backstory was that he isn’t a killer for no reason.
Yuhon killed the priests because they found out Yonhi’s secret lineage, a secret he promised to keep. He’s hated the priests long before meeting Yonhi, as they stood higher than the power of an emperor, as well as people relying on the will of gods. Il was the prefect example of how one relied on the gods too much. Il fully knew about Yuhon’s stance on religion, yet dared to accuse Yuhon of keeping Yonhi’s Hiryuu blood to himself. You guys aren’t understanding that Il intentionally sat back and let Kouka fall into ruin because Yona was Hiryuu. He intentionally let Kouka suffer for ten years because he was relying on the dragons, the gods, to protect Kouka instead. Yuhon’s speech before his death was true, that if Il refused to rule as a rightious emperor and rely on the gods, Kouka will suffer.
As well as Kashi’s death, I don’t think Yuhon killed her. We know Yuhon’s character. Unlike before, we’ve seen him and know who he is and his morales. He kills, but usually for a bigger reason. And WHEN he kills, he doesn’t hide the fact he had spilt blood. Why would Yuhon, who has been known to kill thousands including women and children, hide the fact he killed one woman under the guise of bandits? It makes no sense. Remember, he lied about knowing that Kashi was a priestess, and confirmed that the escape of one priestess was of no significance. Yuhon vowed he would not meddle in Il’s happiness anymore, which was most likely another fact as to why he would not kill Kashi. He knows Kashi is Il’s wife, and that she made Il happy. He has no motive to kill her, and hide her death behind bandits. It’s out of character.
For nearly two hundred chapters, we’ve believed Yuhon had killed Kashi.
And Kusanagi-Sensei knows this.
The format of events—Yuhon being told Kashi was a priestess, and then she suddenly dies? It’s too convenient, and too easy. It’s a red herring, a misdirect. If anything, I believe the most probable suspect is Hyuri, Soowon’s guard and sword instructor. We’ve seen him approximately two or so times throughout the whole manga. Chapter one when he attempted to attack Yona. Right before the flashback arc in Chapter 188, we formally meet him. Yona had noted how terrifying and bloodthirsty he was, how it seemed like he wouldn’t hesitate to kill someone. There’s no reason for Kusanagi-Sensei to name him, and we know of her track record of named side characters having relevance to the story. She wouldn’t have brought Hyuri up if he wasn’t important.
This is why I believe Kashi’s killer isn’t Yuhon, but Hyuri.
Kusanagi-Sensei knows we’ve suspected Yuhon since day one. How crazy would it be if she used our prejudices of him against us?