On the Way to a Smile is a set of three short stories told by Barret, Tifa, and Denzel. The events take place between Final Fantasy VII, and Advent Children.
Each person is trying to atone for their "sins" of their past, and move into the future with the rest of the world. Each story tells their own perspective of that point in time, during the two years.
The Novel was released in the Collectors set of Advent Children in America. This small book is simply titled "The Novel". It is actually a neat piece of work. It depicts what each character is going through, during this difficult time. They were given the same treatment and care, as if were a game/film production.
Written by Kazushige Nojima, Denzel's story was released in episodes on the official Japanese Advent Children website, while the entire story was released in V-Jump's Final Fantasy VII: Advent Children Prologue book. Barret's story was added in the Collector's set, in America.
Each story is a great addition to the history of Final Fantasy VII. They are really worth the read. You can check each one out below.

Case of Denzel  Case of Tifa  Case of Barret