12화: 체내 변화 속에서 새로운 훈련 임무를 맡게 된 레드 블러드 셀
2018년 9월 23일 방영
Red Blood Cell is assigned a new responsibility… To train a new Red Blood Cell! As the senpai, she has to be more anchored and reliable. But while trying to guide the new Red Blood Cell, she makes wrong turns, gets in trouble with the other cells, and things do not go the way she hopes… Meanwhile, there is something happening to the body that could change their world. (Source: Aniplex USA)