It's the way the base is written/performed that makes me think more of Kajiura. That rapid continuous playing of 8th notes and changing the pitch only with the chord movements, with almost no variation, is very much Junior's style of playing, at least for FBM songs.
We'll see.
From listening, I'm kind of with @Azokad ATM - the first one being YK but the 2nd version maybe an arrange by one of the other two...
but if they say it's all YK... I'm excited to hear how it all turns out.