User blog comment:Godisme/Everything But The Rain/@comment-2120712-20130305093603

My impression of it all is that even though he was in a gigai, his powers were lingering, going away over time. That is why each child he had, had less Spirit sensitivity or presence. Isshin could also be the 19th division Captain before Hitsuguya but after TBTP. Ichigo's orange hair and last name as well as partially Quncy biology could of through off the shinigami in recognizing his pedigree. If Isshin is a Shiba, then maybe his abandonment of his post as Captain was the final nail on the coffin that caused the Shiba clan to fall grace. Either way, I can see him being 10th Division in some form. Of course we don't know who took up Captaincy of the Divisions as TBTP and before the current generation, so he has just as much chance of being a captain from one of the other divisions except the 11th.