Yep! Not really sure on the details, but considering what I've heard about a jutsu that got made before I was born that could call back the souls of the dead? Nobody knows how it works, it was slapped with forbidden pretty fast, with good reason I guess, but it's pretty hefty proof for the entire 'the soul isn't gone' concept. What I know of it meant that the person was definitely the person, whatever they were like before, unresolved issues, everything.

Then again, considering there are seals that would let one barter a soul directly with a shinigami, they have to do something as well in regard to the soul, too. I don't know how those work either though. I never got that far in learning seals myself, but sensei would have known.

Either way, if someone can be called back from somewhere after they die, they have to go somewhere in the first place.