The film is set between the 517th and 518th installments of Akira Toriyama's original manga. Specifically, it is set during the "lost decade" of story time after the end of the battle with Majin Buu. Kuririn, Piccolo, Vegeta, and other familar characters will appear in the film. The film is not a spinoff, but a story in the official history of Dragon Ball.
[Source: Anime News Network]