Board Thread:Questions and Answers/@comment-6207546-20130504124857/@comment-8986886-20140702155249

From what I understand of the placement of the different divisions, it can take hours to go from one division's compound to another division's. Since the different squads tend to keep to themselves, it's possible that Rukia never even met Isshin in person, while he was still a captain, and only knew him by name and rank.