S1, E2: Eunseong, a suicidal student, receives treatment from Kim Yohan. Park Muyeol and Lee Jaegyu are looking at documents from a former math trip while Yun Su chases after a blue-spotted corner monster. Meanwhile, Kang Mireu, who did not receive a letter, begins pestering Jo Yongjae, who believes he's been expelled from the school.