Babel Novel Volume 4 was written by Kuji Furumiya.

Having overcome the strife in Kisk and returned to Farsas, Shizuku sets about a new job—making language learning resources for children. Meanwhile, Erik continues to try to help her find a way to get back home to Japan and stumbles across one of the interlopers' cursed tools, a book filled with hidden secrets of the world, in the most surprising of places. Yet this is only one of a pair, and elsewhere, the possessor of the other book, the evil mage Aviella, suddenly declares war on the entire continent! What fate lies in store for Shizuku at the end of her journey…?!