[ChaosDimension]

Spoiler for Why:

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?

Spoiler for Culprit's Background Story:

So here's my theory on Kyrie's story. I'm assuming it'll have holes and stuff since the whole ordeal with ange/battler's true mother as well as miscarriages and stuff are confusing. But here's the gist of it.

-Kyrie is the Heir to the Sumadera she has an arranged marriage with someone and is jealous of her sister.
-Kasumi, not being the heir is free to pick who she wants to marry, since she senses her sister's jealousy, she goes under an assumed name, Asumu.
-Rudolph and "Asumu" meet and have Battler.
-Kyrie finds out Kasumi's relationship somehow and threatens to kill Kasumi blackmailing Rudolph as well as blackmailing her sister. This turn of events force Rudolph to marry Kyrie and have "asumu" die.(How? I don't know, let Ryukishi finish it for us)
-Kyrie and Rudolph marry. Battler leaves Ushiromiya name. Kyrie is disgusted by this and has no proper heir. Thus they plop out Ange. Battler comes back to the registrar after 6 years. Again Kyrie is disgusted by this. Kyrie makes Ange pretend she is "sick" and does not come to the conference.
-Kyrie plans for Rokkenjima Massacre, and succeeds.
-Kyrie gets gold, loses heir to Sumadera becomes free. Her true daughter becomes heir to Ushiromiya and becomes head. What an ideal ending for Kyrie and Ange isn't it?

This answers some of those wierd conundrums that are presented in the early eps. Like how Rudolph knew that he was gonna die. As well as why Battler's sin has nothing to do with Beatrice(the sin was between him and Kyrie).