Board Thread:Questions and Answers/@comment-27449779-20151222131224/@comment-27482127-20151227114001

It wasn't really that he had to be told but more or less he didn't care for Hitsaguya so he didn't want to remember him. Because when she reminds him he stats. "Oh yeah that Prodigy kid."

He knew who he was, he just didn't care to remember. Or since Rangiku wasn't part of his class, he didn't really check to see which squad she was in.

Its like any military service you need to know your chain of command. Especially someone like Hitsaguya who looks like a kid and if you didn't know who he was, you would mistake him for a lost kid. And that would be bad news for you.