Nurse Ahn Eunyoung has been working at School M not long ago. All this time, for some reason, she does not strive to get into the circle of local gossips, find out the reason for the lameness of the hieroglyphics teacher and drink tea with the other teachers during breaks, like her predecessor. Instead, the girl carries a toy gun and a rainbow-colored plastic sword under her medical gown in her belt to fight evil spirits. Ever since she was a child, Eunyoung saw the world differently than others: the lonely jelly-shaped ghosts that lived in the wall of her house or on the playground, the traces of ectoplasm left behind by human regrets, unrequited love and sudden death. Armed with positive energy, nurse-exorcist An Eun-nyong, together with the hieroglyphics teacher, who turned out to be the owner of the strongest shield against spirits, fights various evil spirits that have settled in the school. Will they be able to protect children?