[THAT's the book that Lewis has been reading religiously for the past year.]
Neoma clicked her tongue while looking at the floating black book in the middle of Sir Glenn's room.
To be precise, the black book was floating while pages were being flipped at an unusually fast pace. It was inside this transparent sphere surrounded by black smoke. She could tell that the smoke was from Trevor's Mana. It was similar to the vibes that she got from the Devil's Grimoire after all.
Apparently, a year ago, her son asked Sir Glenn to help him train. Since Lewis wanted to keep it a secret from her, he would go to the older knight's room and open the book there instead of in his own room. After all, Lewi's room was next to her. The little cub was probably afraid that she'd catch him if he opened the book in his room.