From the introduction: In a significantly more peaceful version of Konoha, the Uchiha Clan Massacre never took place. Itachi did not become a missing-nin, Sasuke wasn’t traumatized, and presumably Danzo and Tobi lack a dozen spare eyeballs. What change brought this about, I have no idea. Still, we should be glad it happened. Itachi will be getting a significantly happier ending, what with marrying his girlfriend and becoming an academy teacher.