AE3803 is tasked with delivering nutrients but has gotten lost. AA5100 surprises her and tells her that she is heading in the same direction as her and offers to show her the way to her destination. As they are about to walk, they hear the Platelet Division down below. They are carrying a large package and carefully descend down the stairs.
Platelet is carrying some coagulation factors when one of them falls over, which AE3803 picks up and returns to her bag. She then decides to have the division wash the fibrin at the canal. As AE3803 and AA5100 are delivering nutrients, some rumbling causes the cells to trip. AE3803 asks AA5100 what just happened, and she is in the process of explaining what happens when another rumble causes the cells to fall down a bit. An explosion is seen in the distance, which has left a gaping hole in the middle of the city.
AE3803 gets back on her feet just as she and the other blood cells start getting sucked into the hole. However, she is saved by U-1146, who grabs her in the nick of time. The two recognize each other from a previous incident and he brings her back to safety. AE3803 asks him what is going on, and he explains it to her as he grabs another blood cell; it is an abrasion. If they fall through the abrasion, they have no chance of returning to their own world. He continues to explain that it will be patched and that they have to deal with some germs. Peering over the wall, he notices a germ is about to attack and pushes AE3803 and AA5100 down, saving them from a fatal strike.
A group of germs have appeared, with their leader being the Staphylococcus Aureus. Aureus orders the germs to attack; one tries to attack, but is wounded by U-1146. He tells the cells to run; while AE3803 is concerned for his safety, they cannot assist him. They inform the other red blood cells of the threat, and as AA5100 is informing them, two germs burst in; Streptococcus Pyogenes and Pseudomonas, who demand the red blood cells to give up their nutrients. The red blood cells try to flee, but are blocked by a venous valve. Pyogenes grabs a red blood cell and attempts to make an example of her if their demands are not met. Pseudomonas is cut down by a Neutrophil, while another two kill Pyogenes. The three Neutrophil ask the red blood cells where the abrasion is, and AE3803 points in a general direction, getting their thanks.
U-1146 is battling four germs when one hits him in the back, causing him to drop his dagger. He grabs the germs's thorn arm and smashes it into its face, killing it. A cockroach-like germ then immobilizes him, telling his comrades to move further down. The germ states that he cannot get through his thorn-like arms, but U-1146 surprises it by breaking one of them and smashing the fragment in its face, killing it. U-1146 wonders why the germs are fighting them, as they could have easily spread out. He is then contacted by a fellow Neutrophil that U-2048 need assistance and that he should watch his back. U-1146 heads towards U-2048's position while pondering what the germs are planning to do.
U-2048 is overwhelmed by the germs, but U-1146 arrives and saves him and two red blood cells. The Neutrophil backup arrives just as Aureus summons more germs. The draft then appears and drags U-4989 down the hole, while U-1146 yells to him to keep his L-selectin on. Aureus attacks the Neutrophils, and comments them as such. U-1146 is impressed that she has done some research on them, and she states that she head rumors of a specific Coccus not filing the joint when he invaded, to which another Coccus asks an unimpressed one if that was his brother. Aureus states that she knows all about the white blood cells; the Neutrophil being the first to arrive at an abrasion, followed by the Macrophages and Monocytes, and finally the Lymphocytes. She then resumes her attack, managing to disarm one Neutrophil and wound another. She then attempts to attack U-1146 but is unable to hurt him.
U-1146 states that while she had done her research on the white blood cells, she had overlooked an important cell that stops abrasions; the platelets. They arrive on scene and thank the Neutrophil for their hard work. Aureus, a Coccus and another germ look on unimpressed by their appearance. The platelets descend down the abrasion and apply the coagulation factor onto the fibrin before laying it across the wound, covering it. A germ informs Aureus of their situation and she looks down, realizing that the platelets have clotted the abrasion, preventing her from summoning more reinforcements. With the abrasion covered, the Neutrophil easily overwhelm and kill the remaining germs, with U-1146 finishing off Aureus before falling into the fibrin net. He then notices that U-4989 has survived, having clung onto a metal rod.
AE3803 descends down a rope to personally thank U-1146. He asks her if the other cells are okay, and she tells him that they would be coming over later to personally thank him. She notes that he hasn't moved a muscle yet and tries to leave, only to find that her hand is stuck to the fibrin netting. She then watches as the platelets drag her senpais away; she and U-1146 are also added into the mix. He explains to her that whenever an abrasion occurs, until the outer cell wall is fixed, cells are used to cover the hole, which is called "secondary hemostasis". AE3803 asks him how long they have to be in this state, and he states that it will take around 3 days before they can leave. A large amount of cells have been used to cover the abrasion, while Platelet states that when the clot dries, it will become a scab.
For some reason, after the Platelet gather everyone for a clot, all of U-1146's blood stains disappear.