I still not read Gantz :P I am going to start, so I was looking around seeing what and all published, licensed, scanlated, what is availabile to read. So yeah these chapters and all confusing, not exist properly, individually and not everywhere. Maybe one exists but I thought I combine everything as one which could be easy :) Now it's perfect ;) All of this is scanlated by "Utopia Scans" back then. For the Gantz/Osaka IDK exactly whether they scanlated that two entirely new chapters alone which released in the 3 volumes. But this is all that exists from the past, so yeah that's that. Resource links: https://myanimelist.net/manga/24530/Gantz_no_Moto__Oku_Hiroya_to_SF_Eiga_Monogatari https://myanimelist.net/manga/25824/Gantz_Nishi https://www.mangaupdates.com/series/wdref47/gantz-no-moto-oku-hiroya-to-sf-eiga-monogatari https://www.goodreads.com/series/228795-gantz-osaka-limited-edition https://en.m.wikipedia.org/wiki/Gantz