^ I think it's safer to assume it's three questions per letter. Though we could try and add some more, you never know she makes an exception for a group letter from international fans.
If we have to pick questions, my favourite is still this:
- How long have you been planning to make Shima a traitor?
It's not something we can find out without her telling us, so I'd definitely like to ask.
Another good one that was posted in this thread:
- Which percentage of the human population can see demons?
As for the last one, I'm still curious if Rin realises that the Demon Kings are his brohers... but we will probably find out sooner or later anyway, so feel free to pick another one if people have better suggestions.
Oh, maybe we could include 3 questions for Kazue and 2-3 for the characters? That sounds kind of reasonable.