Cells at Work! Code Black

Red Blood Cells are summoned to handle an emergency. They carry as much oxygen as they can to the scene, but they discover that the stomach has an ulcer and is badly breached. If the serosa becomes perforated, the stomach will end up melting down. Due to the excessive secretion of gastric acid, the body may die at any moment, but the Red Blood Cells continue to desperately carry oxygen. However, the gastric mucosa is being eaten away, and inflammation is getting worse. In such a disastrous situation, a dangerous enemy appears.

Red Blood Cell (AA2153) repeatedly sees flashbacks of his fellow Red Blood Cell (AC1677) falling into a sea of gastric acid and beats himself up for not being able to save his friend. However, this body does not have the wherewithal to let Red Blood Cell recover. While lack of sleep and exercise is pushing the body into a state of disarray, a sharp and huge inanimate object is found floating midair. An attack from a mysterious germ begins...

Still unable to find meaning in his work, Red Blood Cell (AA2153) is determined to continue delivering oxygen and works hard at his job. Contrary to his determination, the body's internal environment continues to decline. Plaque, which is made up of cholesterol and fat deposits, has accumulated on the inner walls of the blood vessels, causing them to deteriorate. The buildup of plaque has even affected the coronary arteries which wrap around the heart and supply oxygen and nutrients to the entire heart muscle...

Bodily functions are coming to a halt. In this dire situation, all the cells are on the verge of losing hope, but only Red Blood Cell (AA2153) hasn't given up. Are they making us work hard because the body is unhealthy? Do we stop working because the body is going to die? After experiencing various diseases and losing his friend, the answer that Red Blood Cell (AA2153) and the other cells find is...