Yusa

Yusa is a member of the SSS who conveys the state of the battlefield to Yuri and acts as Yuri's personal secretary of sorts.
In Heaven's Door, she was once a girl who used a pair of scissors to display her intense hatred towards males, responsible for a chain of murders involving the male student population of the Afterlife School. After receiving words of reassurement from Yuri, she joins the SSS as one of its first members after its founding.