Nogizaka Haruka no Himitsu centers around Y?to Ayase and Haruka Nogizaka. Y?to is seemingly ordinary, but Haruka is attractive, intelligent, and rich, which prompts other students to idolize her and even give her French nicknames like “Nuit Étoile” (The Silver Star of the Night) and “Lumière du Clavier” (The Shining Princess on the Piano). One day, Y?to wanders into the school library in order to return a book and accidentally stumbles upon Haruka’s deepest, darkest secret: