AE3803 becomes tired of always getting lost and resolves to circulate the body without guidance. After a difficult journey, she manages to travel through the heart, then the lungs to exchange carbon dioxide with oxygen, then to the body's cells to exchange oxygen with carbon dioxide. U-1146 clandestinely followed her and helped return her dropped notes and hat, then killed some germs who tried to ambush her, all without her noticing his presence. U-1146 later tells Killer T Cell that he has gained an appreciation for all the hard work the Red Blood Cells do every day and hopes the immune cells can live in harmony with other cells, but Killer T Cell angrily punches him and orders him to get back to work. AE3803 meets U-1146 and tells him how her day went. Killer T Cell walks around seeing several immune cells mingling with other cells and irritably denies being envious.