[Patchwork Chimera]

There's an interview were Ryuukishi07 said "Yes, it was Battler". All the hints point to "Yes, it was Battler". There's not a single line that questions or negates the "Yes, it was Battler"

What in the world is so hard to catch about the "Yes, it was freaking Battler" confirmed by the word of god?

Ikuko is regarded as an oddity. For all we know, she's a real witch that tought funny to try and spread Rokkenjima's cat box. Ikuko=Yasu is less likely that Yasu stumbling around as an amnesiac -because, you know, she was in the Rokkenjima big boom and she couldn't have so swiftly gone and buy a house, identity and all that jazz in so little time-.

Yasu wouldn't have escaped of the Big Boom even if she could. Because that's all her character is about and is been hinted for the enterity of the series: that she was all for dying with them if nobody solved the epitaph. And if they solved it... if they solved it she would do nothing and let them do as they pleased. In case of Battler, George or maybe even Jessica solving it, she'd let her funiture die and take the identity for the winner... and let them do as they pleased with her. Disturbing contents included.

BTE, there's a difference between assuptions made on shaky fundations and freaking castles in the air.
And there's difference between something unlikely but possible inside the game and bullshit from an asspull.