User blog comment:Xilinoc/Ch. 543 - Letters/@comment-6904925-20130627213403

You know I remember something in the Spoilers for this arc saying "Specially Mayuri’s research on bodies will be key in this arc", so then these Vandenreich Quincies as people are suggesting, they could actually be the souls of Quincies instead, except these souls headed to the Vandenreich state instead of the Soul Society.