Peke J (ペキ J, Peki J?), formerly known as Excalibur (エクスカリバー, Ekusukaribā?), is Chifuyu Matsuno's cat. Peke J has black fur and wide eyes. He has a scar at the back of his head and wears a white collar with a cross hanging on it.Although he follows his owner Chifuyu's orders, Peke J has been shown to be a mischievous cat. Despite a month of inhabitance at the Matsuno family's home, Peke J would frequently sneak out of their dwelling to visit Keisuke Baji, who once lived in the fifth floor.