You know how in Call Of Duty 4, when Al-Asad was supposed to be the guy who all of America hated, only for him to end up getting cornered by Brits? I think DOA4 is more "Death Of The Author", by comparison. TBH, I think we're supposed to believe Christie shot Helena's mother, not Ayane.
Well, Ayane is assumed to be the killer because I guess she showed up to the very same opera house. Helena only knows her as the assassin Nyotengu of Miyama. Ayane doesn't help the situation by just saying that she may or may not have been the killer because she's killed a lot of people and just doesn't remember (For her, it was Tuesday).
I remember a Kasumi fan explaining how they believe DOA2, 3, and 4 only happened because Ayane was a smart ass to Helena during DOA2 and Helena everything done to the ninjas in 2, 3, and 4 was because Helena was mad at Ayane for what she said. Blamed everything on Ayane.