One day, while White Blood Cell (Neutrophil) is busy exterminating germs, he meets Backward Cap, a Platelet who wears her cap backwards. She is secretly training to become a stronger Platelet. However, a huge rumbling noise suddenly echoes inside of the body followed by violent shaking.

Memory Cell sees a dream where the arrival of messengers from the outside signal the end of this world... As if his dream became reality, unidentified enemies enter the body! Does Memory Cell not only have the power to remember the past, but also predict the future now? Will this world be ruined as Memory Cell predicts?

Toxic reaction found on the epidermis! Mast Cell does her job according to the manual, but complaints pour in from other cells that are annoyed by her actions. Mast Cell loses her cool and unleashes her rage... An incident occurs where an unknown entity breaks through a blood vessel and the blood cells get sucked away!

An incident has occurred in the body! The Immune Cells rush to the scene and fight the cells infected by a virus. An Ordinary Cell observes this everyday scene with a bored look on his face and says to himself, "I want to heroically save somebody and have them say to me, 'Thank you for helping me.'" A group of mysterious bacteria appear in front of the Ordinary Cell and...

Ordinary Cell heads to the intestines with White Blood Cell (Neutrophil) to reunite the lactic acid bacteria with their friends, but they get separated from one of the bacteria on the way there. Ordinary Cell desperately searches for the lactic acid bacterium but is attacked by cells infected by a new virus!