[Despite the fact that she's acting like she just saw something that shouldn't exist, it seems like it takes Fret's suggestion to make Nanami's brain fully catch up with the implication.]

...But if she was a ghost, she wouldn't be here, right? She'd be in the other place?

[The only spirits that have crossed the lines between the lands of the living and the dead are monsters, after all.]

Maybe this is some kind of second chance.