And before anyone lynches me over the "bankai" remark.
Actually it's not really equivilent to a Bankai. More like shikai than anything.
And by the way the "soul release" Dee mentions goes back to his first appearance in chapter 2 which is dated before season 2 of bleach where the whole concept of "Releases" began.
So yeah AntiBunny was first in that regard. I thought of putting this whole explanation in the comments but because "Bankai" has been a running gag with a friend of mine I thought I'd throw it in there.