Why is ¨ The Jungle Book " such an important part in this story?

The Jungle Book plays a key role in this story because it is a backdrop to the main character´s life. It plays role in the grandfather Leonardo´s childhood and life as well as in his story of the Tiger´s wife and Natalia´s childhood. The book was given to the grandfather as a gift when small and then he used that to show his village that the devil walking around was actually a tiger. He also compared his current life situations to the book and put himself in Mongli´s place. These situations take place during the time of the tiger´s wife story and help build it up. The book is later used to bet with the deathless man, it is the reason why they see each other more than once & hints why the grandfather did not want anyone to know where he went or who he was with when he died. Also, the book was used to bring Natalia up during her childhood.

Why is the "Jungle Book" such an important factor in the story?

The Jungle Book represents NG's imagination, creativity, and knowledge. It is also mentioned as a personal item that was missing once NG's body was recovered back to the family, also was made as a big deal because the forty day ritual was interrupted. One of the main reasons the Jungle Book stands out to me so much is because of its mysterious effect it has on Natalia. Natalia acts as if the Jungle Book was her grandfather's personal bible because when she refers to it, shows the uttermost respectful qualities and recalls beautiful (detailed) memories. The bet with the deathless man intertwines with the Jungle Book as well because they use it when making the bet to prove the deathless man cannot die. It leaves a mysterious thought after the deathless man comes out from the water after an hour, unchains himself, and does not take the Jungle Book but tells NG, he will see him in the future. Hence, when NG's body is found, there is not Jungle Book.