Kakashi got sharingan in both eyes during the 4th shinobi war. In the episode 473 you can see kid Rin meeting kid Obito and obito says her that kalashi is helpless and he is going to give him his sharingan for sometime. He says “chakra is an energy at connects two worlds” so using chakra he comes back to living world.
Kakashi got his Sharingan during the Third Shinobi World war from Obito Uchiha, who gifted him to replace his lost eye after getting trapped in the cave. However, he lost it during the Fourth Shinobi World War when Madara snatched it to transport himself to the second Rinnegan from Obito to get his powers.
9 Gon Freecss (12 Years Old)
Kids from ages 7 to 9 are okay to start reading the first few books. Harry Potter is 11 years old in the first book and 17 years old in the last book. It may be a good idea to align the books to your child's age. The later books in the series get darker and longer.