Gantz:O

Masaru Kato is stabbed to death while trying to help a stranger, only to wake in a Tokyo apartment beside people who should also be dead. A black sphere called Gantz equips them with weapons and suits, then transports the group to Osaka with a brutal command: kill the creatures marked as targets before time runs out.

Kato has a younger brother waiting for him at home, so survival is more than a game. Forced into battle alongside the experienced Nishi, Reika and Suzuki, he refuses to abandon civilians even when stronger veterans care only about points. Osaka's monstrous hunt becomes a test of whether compassion can survive in a system that rewards killing.