Konyaku Kaihi no Tame, Koe wo Dasanai to Kimemashita!!

Altina who's fond of books starts pretending to be a mute in order to escape the imposed image of her as a "perfect lady" role that's set-up by her older brother and older sisters.
However, that being said, that pretend act will soon be discovered by no other than the head librarian, sir Shijar himself?!
(Source: Kadokawa, translated)