Hataraku Saibou!! Saikyou no Teki, Futatabi. Karada no Naka wa "Chou" Oosawagi!

An ordinary cell longs to be praised like the immune cells who always seem to save the body, so when he sees a group of tiny bacteria being swept away by the currents of the intestines, he cannot leave them behind. He rescues them despite knowing what bacteria can do, only to find himself pursued by White Blood Cell U-1146, who has detected their presence.

At the same time, an NK Cell is following information that suggests a dangerous antigen the immune system has fought before may have returned. What begins as a small encounter with unfamiliar bacteria grows into a major disturbance in the bowels, where the difference between helpful and harmful microbes matters enormously and one of the body's most dangerous enemies edges back into the fight.