According to the 14th issue of Miracle Jump magazine, Gantz manga creator Hiroya Oku wrote that he will be ending the manga very soon. Oku wrote the comment in the authors’ notes section for his illustrated column Origin of Gantz – A Story of Hiroya Oku & Sci-Fi Movies:
Gantz will also reach its final chapter very soon. I’ll give it my all until the very end!
Seems that a number of well-known manga are ending. Hopefully there are other works to be published in the future!