Well I had to think about this for a bit. I was thinking of all my animes and if I would ask any of the characters anything. After going through them all, I hit the last one on my list, Ga-Rei-Zero (last only because my mind subconsciously alphabetizes the order in which I think/list them XD), and it immediately came to me.
I would ask Yomi from Ga-Rei-Zero that if she could change one thing she did in her life, what it would be.
Yomi!!!!! T_T
Damn, now I'm very tempted to see if I can write a letter to the author to see if he knows.
I would ask Edward Elric if he never had a sibling so Al never exsisted, do you think you would travel alone or get a friend or more to travel and help you along? (Though I'm pretty sure he would be dead from trying to resurrect his mother)
because ever since i watched Demon Slayer and read the manga i always had 1 question for Muzan .
Lets say , What if the demons won against all the demon slayers in the final battle , and as we all know apart from the sun and nichirin blade demons can live forever unlike humans and with the demon population increasing without the demon slayers to stop them , humans will go extinct one day ,and when that happens what will demons eat ?