A cold virus doesn't just infect, it corrupts. The mysterious cell in the stylish hat seduces regular workers into sabotaging their own system, turning a boring day into beautiful chaos. You get the educational skeleton of how your immune system works, but the real hit is watching white blood cells and killer T cells try to restore order while the ordinary cells finally have something worth doing. It's a special that knows exactly what it is: a funny break from the main series that doesn't pretend to be more important than it needs to be.

Inside the human body, the regular cells spend each day on the same job: dividing, again and again, with little room for anything else. That dull routine breaks when an odd cell in a fashionable hat shows up and draws them into a scheme of pranks aimed at White Blood Cell and Killer T Cell. One of them, Ippan Saibou, is worn out by the endless grind and happily joins in. For the regular cells, the mischief is a welcome chance to let off their built-up frustration. The stranger's identity, though, remains an open question. The special mixes comedy with action and science fiction.