Kei Kurono is the main protagonist of the anime and manga series Gantz. He is initially portrayed as a self-centered and apathetic high school student who becomes embroiled in a mysterious and deadly game after dying in a train accident. Throughout the series, Kei is forced to participate in battles against alien creatures as part of the Gantz mission, where he gradually transforms into a courageous and selfless leader. His character development is central to the series, highlighting themes of survival, morality, and humanity.