Witch Craft Works

The main character, Takamiya Honoka, is a regular student whose only problem seems to be that he sits next to Kagari Ayaka, the school's #1 beauty. They have never crossed words before, and even a small interaction between them results in her fan club beating him. Yet when a falling part of the school's building is about to send him to the afterlife, it was her that came to his rescue. Except, she was dressed as a witch, using a princess carry to hold him in her arms as she floated on a broom. She continues to protect him using her fire magic until the attempt on his life ends. She tells him it is her mission to protect him, and that now she can finally protect him openly (she used different means to protect him "undercover"). Why was Takamiya attacked, who asked Kagari to protect him, why does she refer to him as "my princess" and what is her fan club going to do to him now that she will be close to him openly?