Because he's inattentive, one of the tanks gets full and explodes, releasing all of the collected evil energy. As this is going on, the teenage 'psyche ogre' who is supposed to be watching over the evil-purification machine in Other World is distracted by his music.
The film begins with Goku fighting against Pikkon in an Other World Tournament. FUNimation has released the film on home video in North America several times as of this writing, the most recent DVD release of the film is part of the Dragon Ball Z Collection Three movie box set. The film was directed by Shigeyasu Yamauchi, and it was released to Japanese theaters on March 4, 1995. Dragon Ball Z: Fusion Reborn is the 12th film released for Dragon Ball Z.
