In the light novel series Itachi's Story, there are several points in later chapters where Danzo suggests to the Third Hokage that they increase Itachi's official age by one year, to allow him to get around age restrictions the Hokage has made on being a captain. When I was reading this, I couldn't help but feel like this was some kind of plot fix to explain an error the author had made with Itachi's age during some event in the timeline. Is this the case? And if so, what was the error? If not, is there another reason the author of this book was so insistent on bumping up Itachi's age?