Board Thread:Questions and Answers/@comment-1754938-20150922055002/@comment-44061-20150923200836

I think this has been talked to death but also answered. But to summarize it up. One we dont know that Rukia is all that much older then hitsugaya for it be significant. Rukia, Momo, Kira and Renji were all in the academy at the same time. Hitsugaya comes in somewhere behind in age but because he is far superior in ability ends up graduating faster then them and ends in a position far above anything Rukia attained up until recently. Two Rukia cant recognize someone she doesnt know. Once again there are multiple reasons for this (she never met him before, he was gone before she got into the gotei 13, shes not likely to know what all captains look like, etc.) Three yes Hitsugaya and Rangiku came to Ichigo's house multiple times the Arrancar Arc yet not once are they anywhere near Isshin. Having read the story he went out of his way not to run into anyone in the Gotei 13 who might know him. Kubo later confirms this is the reason he didnt go to Soul Society and plead with Urahara to help return ichigo's shinigami powers during the Fullbring arc, as he couldnt have someone notice him. There is no plot hole here either. its simply set up so that he is never around anyone from soul society. Even in the fight against aizen nobody else was around they had all been incapacitated.