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!

The antibody information of a cell has leaked. There is tension in the air after NK Cell makes a comment to White Blood Cell (Neutrophil). The journey to reunite the lactic acid bacteria with their friends takes the group to the large intestine. In the intestine, which has been irritated due to toxic gas being released by harmful bacteria, the group meets up with Memory T Cell who was formerly known as "Killer T Cell."