Well, thanks for this chapter. This arc really broke my heart, I feel so sad for kashi and yon-hi. I think Yu-hon kill kashi, because he knows she one of the priests. And since he hate Hiryu, because of the curse, he want to destroy everything related to the crimson king. I believe, Kashi don't came with yona , because she have seen the futur, if her daugther had come with her. But she can't see her own future, so maybe she thought everything would be fine, if she come alone. I'm pretty sure Yu-hon want to kill Yona, since he knows she the reincarnation of Hiryu. And maybe he thinking if he kill her, the illness of Yon-hi going to disappear. Specially, since the ilness start when yon-hi meet Yona and Learn about her identity. (Sorry if my english, is bad, it's not my native langage.)