The plot of Gantz is that some people die and they get teleported to a room with a mysterious black sphere that makes them do dangerous missions about hunting aliens. If they survive the mission they revive but might get called again by the sphere to do more missions. They get points depending on how they did and there are some rewards if they make enough points.
One guy wants to try it out (I don't remember exactly how he knows about it) so he stacks up a shitton of guns, puts on blackface so no one will recognize him, just goes ER on Shinjuku and then commits suicide hoping he will get picked up by the sphere. I remember when he's on the train to Shinjuku there are some black American tourists who want to befriend him but he just ignores them kek
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