C638 What Kind of Tonic Did He Eat?

No one dared to engage with Guo Sihai's comment, yet Lin Yaoyang had noticed something peculiar: Guo Sihai had been facing away, engrossed in flipping through a book.

From a distance, Lin Yaoyang couldn't discern the writing on the pages.

However, he could see that the books were crafted from leather paper, their yellowed pages exuding a strong sense of antiquity