Originally Posted by Mimi-chan
Isshin issue always bothered me. Then I kinda forgot and u reminded me. Cos I've been always thinking that Kubo has some bugs in his story. Cos how come 20 years ago. Take Rukia she has been in Gotei 13 for 40 years(or 50). Isshin 99% was a captain he has a captain robe!! So she wolud definatly know him, and stilll she didn't have any reaction when she saw him. Maybe he was captain then quited, but he still was a shinigami on earth. then he met his wife and gave up his shinigami powers for the family sake. What d'ya think?
The only reason I can think of that she wouldn't have recognized him is the he may have been captain of squad 0, the Royal Guard, or maybe even some more secretiv branch than that which we don't know of yet. Also it's possible that everyone in SS was made to forget about him through Kidou.
Another thing that just occured to me is that he could've faked his death and hidden in the human world to start a family, completely giving up his Shinigami powers. If Rukia had recognized him in that case, it may have been brushed off as coincidence.