On an ordinary evening, college student Genno Kiya (Kazuya Niomiya) reunites his good friend Katsu Kato (Kenichi Matsuyama) from his junior high school days at the tram stop. In order to rescue a man who fell off the rails, the two of them were violently hit by a tram. However, in the blink of an eye, they arrived in an airtight room unscathed. There were also seven other men and a huge black sphere. According to the black ball's instructions, this group of people needed to put on combat uniforms and pick up weapons to assassinate the Onion Star People. Some people put themselves into the killing game for the prize money, and some people were ruthless to survive. At the moment of life and death, the cowardly A Ji and the kind A Sheng had to devote themselves to it, and there were more tests waiting for them. In addition, what secrets does the system called GANTZ hide? This film is divided into two parts, before and after, and is adapted from the original work of the same name by cartoonist Ao Haozai.