If I recall, the author made some stories that Ishidaira had liked as a kid and read with his dad. However, due to his father apparently not working much, Ishidaira's mother left and took Ishidaira with her. For a while Ishidaira tried to find the author's book but for some time he couldn't remember the name until he had some help from the Library.That face at the end doesn't seem like it's about a favorite author...
True, the chapters the TL note references were all about Ishidaira's past, so I hope some interesting stories are coming about his past.If I recall, the author made some stories that Ishidaira had liked as a kid and read with his dad. However, due to his father apparently not working much, Ishidaira's mother left and took Ishidaira with her. For a while Ishidaira tried to find the author's book but for some time he couldn't remember the name until he had some help from the Library.
So right now, I'm guessing having the book is making him pretty nostalgia about his dad, and the reason why he likes to read.