[Jan-Poo]

New theory.

Spoiler for episode5 ending:

Excluding the tea parties the game ends with Natsuhi confessing her crime and Battler saying his usual: "Dame da! zenzen dame da ze!"

I've thought of many interpretations:

1) Battler is finally elaborating a counterargument to destroy Erika's thesis, after an incredibly long delay.
2) Battler really is the "man of 19 years before" and he's not pleased enough with natsuhi's confession
3) Battler doesn't buy Natsuhi's reconstruction of the events of 19 years before


And it is exactly this third option that I base my theory upon. Natsuhi didn't kill that young servant and the baby. It wasn't her.
Battler must have found a hole in the narration that made him sure that it wasn't possible for her to be the real culprit.
So in other words there is this person "X" that killed he child and the servant.

but I've got more.

Beatrice's death in 1967 wasn't an accident either. Rosa believes that Beatrice didn't pay enough attention even though she repeatedly tell her to do so. But the truth is. Someone pushed her. And that person is the same person that killed the baby.

Also. Kinzo knew who that person was. And that's why he wasn't pissed at Natsuhi.

Most probable culprit: Kinzo's wife.