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Best friend of Corrector Yui.
Near the end of season 1, she turns out to be the real chosen one in the very beginning. This kind of news really upset Yui, as she loses her Corrector status. This is all just part of the plan for Grosser to control Haruna. However, thanks to that, Yui gets her Corrector status back and saves her best friend. After these events, Haruna quits being a Corrector.
Later in season 2, Haruna has once again become a Corrector when Yui has turned to stone, putting her in a coma from the real world. Unlike Yui, she manages to use the Elemental Suits efficiently. She stays as a Corrector for the remainder of the season.