Gantz | production
Hiroya Oku first thought of Gantz's story when he was in high school. He was inspired by the
When creating the chapters for the manga, Oku starts with a thumbnail of the pages. He then creates 3D models of the characters and backgrounds on his computer. Once done, Oku prints the characters and backgrounds he made in 3D, adds tone and color to the pages, and finishes with sound effects and dialogue.  This style was already used in Zero One, but for that title, there was little work in hand drawing; Oku decided to add more hand drawing to give Gantz a more realistic tone as well as reduce the budget. However, he still notes that such a method is time-consuming and that he has to work quickly in order to finish the chapters on time. 
Oku tries to incorporate realism into Gantz and adds that some of the events occurring in the story are based on his opinions regarding the world. During violent or erotic scenes, Oku makes sure to not make them very long to avoid reducing the series' realism. However, he has mentioned that he does not autocensor and that all the drawings he has ever illustrated have been published in the manga.