In chapter 7 of Kuroneko to Majo no Kyoushitsu , Spica and Claude discover that their classmate Castor shares his body with a twin sister named Pollux. Pollux demonstrates superior magical abilities and reveals a deep resentment toward Claude for past events. Read a detailed summary of this chapter at The Classroom of a Black Cat and a Witch Wiki . Chapter 7 | The Classroom of a Black Cat and a Witch Wiki