Birthday: December 25
Blood type: O
Height: 152 cm
Weight: 43 kg
Isurugi is Taro Sado's senior. She is the head of his school club and is violent to Taro due to her superiority complex. She is a self-proclaimed deity. She also has ailurophobia. She is an extreme tsundere, and repeatedly attacks Taro, in an (unsuccessful) attempt to cure his masochism.
Mio does not get along well with Tatsukichi when his alter-ego surfaces while cross-dressing, especially from the fact that Tatsukichi belittles Mio's bust size whenever his alter-ego comes out. She does not quite realize that she has an innate sadistic personality, which may explain why she constantly resorts to violent measures to cure his masochism. She is shown to be very athletic, but has been said by Arashiko to not be very good at studies.