The twintails girl. Look like she is wearing a masked rider belt. May be she's otaku or mutant cyborg that can transform into mask wearer super human.

Shi-chan said that she alway by mimika's side when she in troble and need some help. But in ep1 when mimika lost her purse she hasn't been there to help her like she said al all. I think that why yuzumori said something like that.