The incident came to light through a police investigation, beginning with the testimony of a girl named Jun Taniguchi. She was taken into police protection and stated that, based on what she witnessed, the bodies of two men were discovered in an abandoned factory. However, due to the chaotic circumstances at the time and her own visual impairment, her account lacked precise details. As a result, investigators only confirmed that a girl had been assaulted and that one man had been stabbed by an unknown person. Two months passed with the investigation at a standstill—until a new witness suddenly came forward. Claiming to be an eyewitness to the "incident," her appearance brought a dramatic new turn to the case.