Douchin is brought to his new class, and Undine follows him there to remain close to Himoi, who is revealed to be an extremely popular teacher, especially among the girls. After several instances where Undine uses her powers to deflect girls away from Himoi, she confronts him. Himoi blurts out that he prefers the peaceful life of the school over her, and Undine transforms the place into a dystopian, tortuous environment. Douchin tries to ask for help from the agency, but everyone refuses. Back at the school, Undine discovers that Himoi doesn't remember saying he loves her, and turns him into a fish. Douchin returns and realises that everything happened because he used Gusion's powers to erase Himoi's memories. He then makes Undine happy to undo her powers and makes Gusion eat everyone's memories to cover his tracks. Back at the agency, a happy Undine tries to force her renewed affections on an enraged Akutabe.
光太郎のクラス担任・紐井は、ノリが軽くて頼りにならないダメ教師だが、女子生徒にモテモテの超イケメン。
そんな紐井に惚れてしまったアンダインは、何かと理由をつけて授業に潜り込む。
そして紐井が女生徒と仲よくするたびに、アンダインは“嫉妬”の能力を発動させる！
