Responses
The uke was actually a descendant of a eextinct clan "Chu" and that clan was very prosperous and has great military tactics. The seme wanted the "knowledge" of military chu and the history records kf their clan are hidden inside a tomb and you need a "key" to enter. Tje key was the "Chu's" descendants pinky finger. (they have extra bone or something)
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The seme was just using the uke, he knew all along what the siblings where planning on doing to the uke. The wife will scheme something later on and the seme will just let it be and will banish the uke so that the king will take him in. In that way the seme will know where the key to something is. He didnt know the uke was the key.