User blog comment:Nick D Wolfwood/Questions questions questions!! Kurosakigate.../@comment-1961713-20100626113732

@Salubri, thanks for your thoughts, anyway if Kubo had used Zangetsu still as Isshin's previous Zanpakuto spirit he would spent few chapters just to tell us about this, personally it is a relieved that Zangetsu INDEED Ichigo's own rights. Now one things remains to be understand is how Engetsu and Zangetsu able to teach those 2 the same technique GETSUGA TENSHOU.

@Nick you right I cannot see all them captains knew Isshin, as of now we only know that Urahara, Yoruich, Ryuken (definitely) and Aizen the only few who have any knowledge about Isshin. This guy is GOOFY but MYSTERIOUS too!!!