Gantz manga volume 1 contains volumes 1-3 in an omnibus format and features story and art by Hiroya Oku.

Tokyo teens Kei and Masaru are struck dead by a subway train but awaken in a room with an ominous black orb that gives them weapons, suits…and orders. Fighting and endless stream of bizarre alien monstrosities in a deadly game, will they win their freedom or die for the final time?