It's a question of perception.

Let's say you were the one who got 'erased.' I wouldn't even be aware that you were sitting here in front of me right now.

Miss Shameimaru would be able to see you, though - for her your birth is an indelible part of her own past.

...So if there really was a murder, the victim must have been older than me, correct?

Yes.

Well, that definitely narrows things down.

Wait a minute... I thought Keine's power didn't affect you?

Do you remember this person?

No...

I don't remember her.

Besides, I'm only immune to Keine's influence for more recent events.

My family exists independent of conventional history, it's true.

But even my previous selves had to consult outside sources to build on that knowledge.

Wait, are you saying what I think you are?

Yes.