The Boy in the Country of the Book is a Chapter 92 of Tsubasa Reservoir Chronicle.
Syaoran has now landed in the middle of a rainy forest and having no idea as to how he got to be there he shouts for Princess Sakura and the others but does not receive a response.He ponders if he traveled to anther dimension but realizes that he could not have done so without Mokona. Then he wonders whether the book given to him by Kurogane had something to do with it and when he leans down to check he notices much to his surprise that there are words written down in previously empty book. As he flips the pages, he gets sent to another place where he notices a young boy chasing after a flying handkerchief and concludes that the boy could not see or hear him. On paying closer attention he is astonished that the boy resembles Kurogane very much.
The boy now runs to his mother and returns the handkerchief to her stating that it was something precious to her. Just then another man presumably the boy's father greets them both and much to Syaoran's amazement is a likeness of Kurogane. But on closer observation he notices that the person's left hand is not injured.
After some light greetings between father and son, the man and his retainers discuss their successful return from their trip around their territory and how they have a good harvest this year. The man also thanks his wife praising her as an excellent priestess whose barrier protects their country of Japan in Suwa. The priestess states that her barrier is not as large as that of the Princess of Shirasagi Castle and the man reassures her that if by any chance monsters were to breach the barrier he would be there to protect them.They begin to reminisce about how closely the boy resembles his father in his youth.
Syaoran recollects that Kurogane was from the country of Japan and wonders as to the identity of the father and son who closely resemble Kurogane himself. The pages turn some more and yet again Syaoran finds himself in another scene where the boy now a bit older hurries to meet his mother scared of the consequences of angering his always docile mother. Then Syaoran finds himself in something that looks like a training exercise between father and son and wonders if he is inside the world of this book.