User blog comment:GinIchimaru/Isshin and Urahara's relationship/@comment-452405-20100405012548

I'm curious as to where Isshin's time as a shinigami took place as Shinji didn't recognise him while Aizen has yet to show any signs of knowing Isshin. I'm not saying the he definitely doesn't know Isshin but so far nobody from the past 110 or more years seems to recognise Isshin other then Urahara. I could be completely wrong here though just let me know if I'm missing anything.