Here are some reasons why I choose Kyrie, she makes the most sense to me and for some reason all the puzzles fit when you put her as the culprit.
-She fits all the ideal culprit qualities I stated in my previous posts.
-Battler
TRUSTS her. By having control and influence of Battler she has a major advantage. She was the one that gave him the idea of "turn the chessboard over" remember?
-She is one of the only "Major Characters" without a backstory. That to me, seems suspicious. That and/or Ryukishi is saving her backstory in the final few episodes. Not the mention some of the stuff that pertains Battler dance around her. Battler's sin, Battler's true mother, Battler being the main character etc.
-She looks to be the most agile/fit/dressed for murder and moving bodies around.
-Is a woman, and can pose as Beatrice.
-Her character bio mentions she's in shady businesses, perfect for turning gold = into real money.
-She is good at decoding the epitaph really well, coincidence? Or was that all preplanned? It's suspicious because kinzo's letters as well as the blood symbols shown throughout every murder are very well done, its like she researched this on google or something and tried to make the whole witch thing reaaally convincing.
-She is least suspected, imo. Which is what probably Ryukishi was aiming for.
-Portrayed as overall ally of Battler and a good person. She doesn't have any evil looking character sprites at all.
-Her motive is incredibly convincing. She is suppose to be the heir of the Sumadera family, but all of a sudden marries into the ushiromiyas. Making Kasumi the heir and her with no responsibilies. Add the allure that the Ushiromyas will be handing out inheritance and she can basically go for a two-fer. Relinquish the heir of Sumadera and grab the gold from the Ushiromiyas killing everyone including faking her own death and bam. I'm rich, and free from responsibility. Is that not the perfect outcome for her or what?