User blog comment:Primeramizery/is it just me, or does everyone else have a feeling that there will be a rematch between uryu and mayuri?/@comment-10630156-20130906124447/@comment-5398287-20130907015323

Urahara doesn't need permission from the Soul King to show up, to my knowledge. He's gone to Soul Society before, namely to ask the Gotei 13 to put their Reiatsu into a sword in order to reawaken Ichigo's power.