Day 4 is the fourth chapter of Heavy Object: 0.01mm War.
- The 37th investigate the infection base and Pathogen X, encountering and fighting Kerukeion forces. On finding deadly mold set up, Catherine is infected in the process of saving Quenser.
- The Object Dionysus/Lizard Tail is revealed to have been dropped under the guise of an asteroid. Following a scuffle with the 37th's forces, it attacks the Gatling 033. With the help of Quenser and the Cronus, it is eventually sunk.
- Pathogen X is revealed to be Argeiphontes, a poison gas developed by Hermes Pharmaceuticals.
- Quenser Barbotage
- Heivia Winchell
- Milinda Brantini
- Froleytia Capistrano
- Catherine Blueangel
- "Oh ho ho"
- Lendy Farolito
- Robert Mistynail
- Baby Magnum (Legitimacy Kingdom)
- Gatling 033/Rush (Information Alliance)
- Cronus/Old Fashion (Faith Organization)
- Dionysus/Lizard Tail (Faith Organization)
|Quenser in a gas mask and Catherine||Part 3 Illustration|
|Dionysus/Lizard Tail||Object Profile|
|Volume 12, Chapter 3||Volume 12, Chapter 4||Volume 12, Chapter 5|