@kamishiniyari I feel like it's probably something along the lines of each "case" in the sinners of the system is its own volume in the same set, and they're separated because they're stand alone stories? Case 1 is only 6 chapters, which is about a volume's worth of chapters. Case 2 doesn't appear to be completely scanlated yet.
If that is the case, honestly I wouldn't have bothered separating them or at least wouldn't make things confusing with the chapter numbering when the pages are so separated they don't even link to each other except via the author/artist links.
@Glomoro , ah thank you, i thought this was a single title , i've just searched the sinners of the system and it seems there are 2 more entries listed on MD. Though yeah, if these volumes are part of the same title, they shouldn't have separate entries on mdex , well, i don't know how things work, i'll just bookmark for now ...
@Glomoro@kamishiniyari thank you both for reading and for your comments. I'm sorry if you got confused about volume numbers. Actually the sinners of the system books are 3, every volume is a stand alone story but they all belong to the same "big" story, infact they are called case 1, 2 and 3. I couldn't put all of them together because I wouldn't have been able to give them the 3 different summaries. Anyway I understand that this can create confusion, especially for someone who isn't much into psycho-pss world, so I'm fixing things. Every volume will be named volume 1, so it will be clear that there's nothing before that hasn't been posted. Thanks again for reading.