When she was a student, Kotone was good enough to win a national swimming competition, so she was assigned to her alma mater as a teacher and advisor to the swimming club. - It was once a prestigious school for swimming, but times have changed and the swimming club has weakened and its survival is in jeopardy. - He was entrusted with rebuilding the school, but his enthusiasm for teaching became ineffective and a large rift formed between him and the students. - Gradually, the rift deepens and turns into hatred, and the students plot something...