Under suspicion of being a spy, a beautiful teacher is placed under interrogation and left handcuffed to a desk when the lead investigator briefly steps away. Shortly after, she is suddenly struck by severe abdominal pain, but is denied permission to use the restroom until the investigator returns. Trapped in this desperate situation, a new female bus guide in a bright red uniform appears. However, the bus company's rookie training is no ordinary program—it's a special trial directed at her. The beautiful teacher is accused of having a forbidden relationship with a student and becomes the central figure in a staff meeting. Despite her intense and growing urge to defecate, she is unable to leave her seat, ultimately facing a humiliating and degrading conclusion.