There is an unspoken rule within the anime community that states “Nothing is canon unless it is in the source material.” In most cases, source material is referring to the manga, though it could also be referencing the databooks, or any light novels the mangaka has written. Because the stories of movies and OVAs tend to not be written by the author they are rejected. However, there are two anime films that challenged this belief. Dragon Ball Z Battle of Gods is the first anime feature film to be considered canon by the fanbase because the entire movie was written by Akira Toriyama even though the events never happened in the manga.