Hazuki Shino

She is Grimm and also the serial killer behind most of the New-Gen cases.
She will be wearing glasses if Takumi decides that he prefers glasses girls while talking to Grimm at the start of the story.
She is a member of the cult detective Ban is investigating, known as the "Cosmic Church of the Divine Light". She kills herself by driving a stake used in the third New-Gen case into her throat.