User blog comment:B214/Volume 23 discussion blog/@comment-177.177.111.64-20170428220132/@comment-29963364-20170501163421

It was from Issei's point-of-view. He doesn't know who Samejima and Natsume are, so, unless they introduce themselves, how the hell is Issei supposed to know who they are.

Just because their names weren't out-right mentioned directly to Issei doesn't mean that they aren't there.