"Code name: Yuna. We've identified an executive of the criminal organization Black Moon. He's the leader of the dark fighting tournament. Contact him and investigate the organization's secrets." After failing an undercover investigation and being captured, Yuna takes part in a fighting event to protect her mother and sister. ...Those who lose will be raped. The female investigator, who tried to make a comeback despite being raped, ends up having her anus violated after her second defeat.