Fuu Inubouzaki

A third-year in middle school and the president of the Hero Club. She is the older sister of Itsuki, who she has been looking after following the death of their parents.

[Spoiler] She is knowledgeable about Shinju and the Vertex and was the one who gave her fellow members the app needed to fight against the Vertex. She uses a large sword in her hero form and her familiar is Inugami.

As a result of using her Mankai form, she loses vision in her left eye. [/Spoiler]

(Source: Wikipedia)