[Jan-Poo]

Spoiler for episode5:

She must be someone among Shannon, Jessica and Kanon.

Most hints lead to either Jessica or Shannon, but Kanon could be the unexpected option.

Personally I think that right now the most probable is Shannon. At any rate the person involved with "Battler's sin" must be her. It seems that the sin is a broken promise, and there seem to have been a sort of love relationship between Battler and "Beatrice" in the past. That's why Jessica doesn't sound right. However it might be that while the subject of this story is Shannon, Jessica is acting on her behalf. Or maybe Shannon is doing the killing and Jessica with her Beatrice personality is covering her.

What doesn't convince me is the fact that Battler seems to consider "Beatrice" and the one whom he made a promise to the same person (despite what she said in ep4). If Battler really understood everything then he shouldn't have mistook one for the other.