Kurono Kei and his ex-elementary school friend Kato Masaru had survived the first two ordeals imposed by the strange black sphere Gantz. Exploding body parts, battling to stay alive until the final seconds, and witnessing your fellow colleagues collapse in a heap of blood and gore have become the norm for them. They are now aware that Gantz can summon them, along with any new deeds, at any time for another encounter with aliens. Will Kato's experiences in the Gantz universe inspire him to be brave in the real world? With fellow veteran Gantzer Kei Kishimoto presently residing at Kurono's house as his "adopted pet," would Kurono be able to resist his growing desire for her mammaries? What exactly is Gantz?