A new virus has been found to primarily enter the body through the mucous membranes around the anus. As a result, "anal health checkups" have been implemented in schools nationwide to accelerate vaccine development and prevent further spread. These examinations are conducted in strict secrecy, with a policy of tacitly allowing certain human rights violations if necessary. Students must follow instructions from doctors and nurses, remove their panties, expose their anus, and undergo the examination on an exam table in a quadrupedal position.