I hate this kind of cliche, like the face I can give a pass (and even then is a stretch) but not recognizing the voice when the both of them interact on a daily basis? And to be honest, even not recognizing the face is too much, the guy barely changed.
Anyway, it is one of the few mangas I've seen lately were the protagonist is not the typical otaku averse to society so I'll be giving this a chance (and I have nothing better to read anyway).