Jun and his teacher, Kurose Katsuko, find themselves drawn together in a secret romance that blossoms within the school walls. Their intimate moment in an empty classroom is unexpectedly observed by Shinohara Kazuya, who seizes the opportunity to gain power over Katsuko through blackmail. Faced with the risk of exposure, Katsuko must confront a difficult decision that could alter her future with Jun. This opening episode explores the tensions arising from hidden affections and unforeseen consequences.