WARNING: The following contains spoilers for Episode 5 of Cells at Work! CODE BLACK, "Overwork, Hair Loss, and Delirium," now streaming on Funimation.
We already got a sense of how overworked and unhealthy the host body was from the very first episode of Cells at Work! CODE BLACK. Even so, Episode 5 is one of the saddest with the stark realization that every single cell is putting in a 110%, single-minded in their focus to keep this body going.
At this point, they're not even trying to help the body get better -- they're in pure survival mode -- but the Killer T Cells take their jobs too far when they start hurting their own.
Calling in the Big Guns
The failure of the White Blood Cells to quickly stop the gonococci cells prompts a fanatic Helper T Cell, who formulates strategies for battles, to command the Killer T Cells to kill virus-infected cells and Cancer Cells. With the White Blood Cells still recovering from their battle with the gonococci cells, the Killer T Cells are none too friendly towards U-1196, since they now have to work in overdrive. Despite being told that the Killer T Cells are exhausted and to get back-up from the White Blood Cells and Macrophages, Helper T Cell insists on sending out the Killer T Cells.
While they're effective, the Killer T cells turn into mindless zombies, chanting "Eliminate the foreign substances." AA2153 and his friend walk through the capillary vein towards the hair root where AA2153 had met the Hair Matrix Cells, who constantly divide in order to produce hair. When they arrive, they're horrified to see that the entire pore is on fire.
To the Red Blood Cells' surprise, this attack wasn't due to a virus or bacteria -- it was because of the Killer T Cells. Because their focus has been to eliminate foreign substances, they have only been targeting cells that multiply, like cancer cells, and didn't realize that the Hair Matrix Cells also divide and multiply but are entirely harmless.
Unwilling to listen, the Killer T Cells continue their attack, resulting in hair being forcibly pulled out due to the stress. Helper T Cell is too engrossed in his mission to protect the body that he's unable to tell the Killer T Cells to call off their attack on the hair root. Stressed and worried about the body falling apart, Helper T Cell, and on behalf of the Killer T cells, take it upon himself to bear the burden of protecting the body.
The Fallen Heroes
Frustrated that the "cancer cells" haven't been eliminated, Helper T Cell activates cytokines into the Killer T Cells, brainwashing them even further. Despite the danger they're in, AA2153 insists that they do their job and deliver oxygen to the hair root in the hopes of restoring peace. Right at that moment, the host body takes steroids, managing to suppress and incapacitate the Killer T Cells and Helper T.
AA2153 watches Killer T Cell struggle against his binds, shouting that it's up to the Killer Ts to protect everyone, and tells him that he doesn't have to work anymore. And it's as if this is the first time he's been told that. It's only then that the Killer T Cell stops struggling and weeps, overcome with exhaustion and perhaps relief.
By no means is Helper T Cell a bad cell: his heart is in the right place which makes it all the more gut-wrenching to see him get overwhelmed by the stress of trying to protect the body. He obviously places a huge amount of trust and faith in the Killer T Cells that he neglects to realize that he's breaking them.
And watching the collapse of the body's strongest line of defense fall like this, not because they weren't strong enough but because of the system itself, is an unpleasant wake-up call for AA2153 who, in his naivety, believed that if he worked hard enough, everything would be okay. Unfortunately, it won't be, when problems keep arising as the host body continues to not take care of itself.