Mizune

Mizune is the surname of a large family of witches who all look alike and whose animal theme are mice. They speak by saying, "chi" (sound of a mouse squeak). One witch from this family is initially introduced as a friend of Eruka's. Like Eruka, she does not like the fact that Medusa has so much freedom and that she brings Chrona to the witch meetings. Mizune and Eruka try to kill her for endangering all witches while she is staying at Shibusen. Mizune is killed by Medusa when Medusa set off her snake bombs that she had implanted in Mizune's body. Five members of the family join Medusa after Eruka tells them that their family member that Medusa killed was actually killed by a Shibusen student.

The five family members can merge into a single being capable of actual speech. The form is of a good-looking young woman with short pink hair with a hat, long skirt, and a shirt showing her stomach and a good portion of her breasts; this exposed portion is most likely where the deceased Mizune covered. (ref: Wiki)