Hikaru Nagihara, a Nankai Academy swim team member, navigates whispered doubts about her athletic skill while maintaining a close friendship with teammate Sae Ichijyo. Her presence on a list of students linked to Professor Yuko’s schedule draws scrutiny during the murder investigation. Covert surveillance uncovers clandestine footage of Hikaru in a compromising encounter with the swim coach within his office. A pivotal exchange between them during this moment inadvertently unveils a critical clue, steering the investigative efforts of the male student group. Though the inquiry employs confrontational tactics and covert methods, Hikaru’s explicit role beyond the recorded incident remains undefined, with no expanded narrative or additional interactions documented.