Gantz: Perfect Answer (2011)

Summoned by a mysterious black sphere, Kei and Masaru find themselves battling a relentless onslaught of aliens. The intense conflicts push Masaru to his limits, and he ultimately decides to abandon the fight, leaving Kei to grapple with the consequences of their mission. As Kei wrestles with his partner's choice, he must confront the true nature of their predicament and the challenges that lie ahead in this high-stakes battle for survival. With tension mounting, the duo's friendship and resolve are put to the ultimate test.