Gantz, Chapter 306

Gantz (Japanese: ガンツ) is a Japanese manga series written and illustrated by Hiroya Oku, depicting a posthumous game. Gantz tells the story of Kei Kurono and Masaru Kato, both of whom died in a train accident and become part of a semi-posthumous “game” in which they and several other recently deceased people are forced to hunt down and kill aliens armed with a handful of futuristic items, equipment, and weaponry. Both the manga and anime are noted for their heavy violence and sexual content.
This is Gantz, a cruel game where the recently deceased must hunt and kill aliens to survive. There is no salvation, no peace, and no god waiting for them—unless the big black ball controlling their fate counts. Thought your life was bad? Sometimes, death is worse.