User blog comment:Xilinoc/Ch. 685 - THE PERFECT END/@comment-1210805-20160805044223/@comment-1210805-20160806080927

And at one point there were only so many captain level Shinigami, but suddenly some less important characters got bumped up, and some dead characters came back to life. There are plenty of instances in the series of people being promoted and moved to a different squad that has an appropriate opening.