I just really wanted Hitomi to meet back up with everyone in the future (maybe not Yuito, that would be awkward. I imagine that grave in the ending montage was probably his). Still, I enjoyed how it went too.
That's what I thought with the grave, but I don't know what they would've done with meeting them regardless. There was already a climax earlier and it might've been hard to incorporate another. I really liked the picture book and I thought that tied things up nicely, although I was kinda expecting some future meetings. Her interaction with granny Kohaku was kinda sweet, though.
Okay but why in the fuck didn't we get to see a picture of the other animals during the book narration. That's the thing I'm most annoyed about with the final.
I also read the graveyard as her mother's, not Yuta's but. ---
"Let's all go play nagasaki. We can all get vaporized. Hold my hand, let's turn to ash. I'll see you on the other side."