Aoba has no interest in anything, not even herself. She is a great student that gets great grades for everything, even for sports. She does not show any emotion. Her smart personality makes Keima acknowledge her as a genius. Because of her talent, there is nothing challenging in her life, therefore she created a gap in her heart. After Keima captures the spirit in her, she becomes addicted to playing gal games just like Keima. And just like him, she also becomes famous in the game world with the name "Maihime".
From kaminomi.wikia