Gantz

The Gantz manga by Hiroya Oku is an adrenaline-fueled ride packed with action, suspense, and dark questions about life and death. When high schooler Kei Kurono and his friend Kato die in an accident, they don't find peace in the afterlife—instead, they wake up in a strange apartment with a mysterious black sphere called Gantz. It pulls them into a deadly game where they must fight bizarre alien beings, earn points, and find their way back to life.