Leviathan is the webcomic/webnovel released as a teaser to Limbus Company.

It focuses on the recent past of the Color-class Fixer, Vergilius the Red Gaze, and the events that led him to join Faust and the other sinners who live on Mephistopheles.

The story is set after Library of Ruina's true ending and epilogue, and bridges something of the gap between it and Limbus Company. However, it does not conclusively answer all questions, nor does it cover all events.

Due to its nature, the story has major spoilers for the true ending of Library of Ruina. If you do not wish to encounter such things without having finished LoR - do that first.

Leviathan was originally made available on Postype. However, as the series is age restricted (unlike the previous ProjectMoon webcomic "WonderLab"), an account is required to access the content, and verification of age. Since the website is in Korean, this presents some difficulties.
In addition, the official EN translation is not yet completed. As the EN translation/localisation team is working on Limbus Company, there is no timeframe as to when we might be receiving an official version of chapters 16-20 in English.
Thus, this guide features the links for all chapters of Leviathan, including chapters 16-20 which have been fan translated and reviewed by @SnakeskinFS and @bluemoon_terror.

If you wish to express appreciation for their hard work, the tweet featuring the fan translation of these chapters, can be found here. Please thank them appropriately and credit their hard work if you do share a link to other individuals.

Official cover art[drive.google.com]

• Chapter 1[drive.google.com]
  
• Chapter 2[drive.google.com]
  
• Chapter 3[drive.google.com]
  
• Chapter 4[drive.google.com]
  
• Chapter 5[drive.google.com]
  
• Chapter 6[drive.google.com]
  
• Chapter 7[drive.google.com]
  
• Chapter 8[drive.google.com]
  
• Chapter 9[drive.google.com]
  
• Chapter 10[drive.google.com]
  
• Chapter 11[drive.google.com]

• Chapter 12[drive.google.com]
  
• Chapter 13[drive.google.com]
  
• Chapter 14[drive.google.com]
  
• Chapter 15[drive.google.com]

• Chapter 16[drive.google.com]
  
• Chapter 17[drive.google.com]
  
• Chapter 18[drive.google.com]
  
• Chapter 19[drive.google.com]
  
• Chapter 20 - Finale[drive.google.com]

• Original Korean on Postype[projectmoon.postype.com]
  
• English TL on Postype[projectmoon.postype.com]
  
• Japanese TL on Postype[projectmoon.postype.com]

The series, its cover art, and the icon used in this guide, are the intellectual property of ProjectMoon. The artwork from chapters 1-11 is the work of monggeu aka @koug99, commissioned by ProjectMoon at the time.

First 15 chapters translated & localised by the ProjectMoon EN team (NEET and CasualWatson).
Latter 5 chapters unofficially translated and reviewed by @SnakeskinFS and @bluemoon_terror.
Parody cover "art" created by yours truly @Aureate54668827

I do not claim any rights to any of the main body of the work, nor do I claim any rights to the translations - the purpose of this post is merely to improve accessibility.

If you have feedback or comments, please let me know.
Should an official translation be released, I will add it to the guide, though out of respect to the fan translators, those versions would remain for sake of posterity.

EDIT: imgur albums now converted into .pdf format for increased convenience. Should now be available without requesting access - apologies for the issue.

EDIT 2: Links to files updated. The links were previously hosted by other individuals, some of which did not have download options available. Wording has also been slightly updated in places.