I feel like nothing really was accomplished with this narrative. Tomo dies and doesn't progress as a character, and Ai doesn't really progress as a character either. She started off bored and disinterested, and she's just as bored and disinterested when the story ends, only with a different excuse.
The idea itself isn't terrible, but I do wish more was done with it.
Maybe that's what the author was aiming for. If that is so then mission accomplished. I started out reading this bored and disinterested. Then I ended reading it bored and disinterested. All's well that ends well.