This is a story that happens inside a human body. One day, as a Red Blood Cell is delivering oxygen and carbon dioxide, she is assaulted by Pneumococci and rescued by a White Blood Cell. To protect the body that’s their world, the White Blood Cell (Neutrophil) chases after the one Pneumococcus who’s escaped

Things have been peaceful for Red Blood Cell when suddenly an abrasion occurs before her eyes. The White Blood Cells (Neutrophils) arrive to battle the bacteria and viruses invading through the wound, but they struggle against enemies like Staphylococcus aureus. Will the White Blood Cells (Neutrophils) find a way to defend this body?

Naive T Cell is patrolling the body for influenza virus proliferation. But since he’s never taken on the enemy before, he’s completely terrified and useless. He finally ends up fleeing the battlefield where White Blood Cell (Neutrophil) and the veteran Killer T Cells are fighting

Bacteria appear near the stomach. White Blood Cell (Neutrophil) is on the scene at once. There, he finds Eosinophil, another type of White Blood Cell, already in battle, but she’s struggling badly

The body has been invaded by a mass of cedar pollen! Rushing to the scene so that he can eliminate the cedar pollen, White Blood Cell (Neutrophil) runs into Memory Cell. Memory Cell is a Lymphocyte who retains the immune system’s memories. Seeing what’s actually going on, Memory Cell is strangely flustered

Let me become a great red blood cell one day. This is the story of Red Blood Cell before she became Red Blood Cell, when she was a young Erythroblast. The Erythroblasts are training hard to become full-fledged Red Blood Cells under the supervision of their teacher, Macrophage

The enemy disguising himself as a common cell has revealed his true identity. He is Cancer Cell. To protect this world, White Blood Cell (Neutrophil), Killer T Cell, and NK Cell must now confront the attacking Cancer Cell in battle

Delivering carbon dioxide to the lungs, and bringing oxygen to cells throughout the body. That’s Red Blood Cell’s important task. Though she’s still directionally-challenged and always losing her way, she can’t be a fledgling forever

In the middle of a drill, Killer T Cell tosses a subordinate right into Helper T Cell’s office. The two polar opposites start arguing. According to Dendritic Cell, although they play very different roles today, they were actually classmates at Thymus School

Red Blood Cell is being chased by a germ! The one to come to the rescue is a masked Monocyte. Apparently, they are also part of the White Blood Cell family and a type of Immune Cell. There’s no way Red Blood Cell could be attacked by bacteria twice in one day, but she encounters another one on her way to the nasal cavity

The world (body) is engulfed in sweltering heat. Even after triggering sweat, the body can't be cooled down. Abnormal increased vascular flow, soaring fever

Red Blood Cell has been assigned to train a rookie Red Blood Cell! She resolves to “show her what a dependable senpai I am!” But she keeps losing her way, and getting yelled at by other cells, so it’s not going very smoothly. Just then, a major incident rocks the world inside the body

"We have detected life-threatening damage!" Hearing of this emergency, White Blood Cell (Neutrophil) rushes to the blast area. But there, he finds no traces of the blood cells he's supposed to protect! Due to massive bleeding, a huge amount of blood cells have already been flung outside the wound. And the bleeding continues