18+ Nogizaka Haruka no Himitsu

The main character, Ayase Yuuto is your average boy without any special traits. He attends a private high school where he is one of the many and doesn't stand out, until, one day, he happens to discover the secret of the school princess Nogizaka Haruka, and his life changes drastically from there on.

Haruka, the school's most unattainable girl, is so idolized in the school for both, her looks and intelligence, that her classmates nickname her Nuit Étoile (The Silver Star of the Night) and Lumière du Clavier (The Shining Princess on the Piano). However, nobody knows that it is only a fake role she assumes to hide her true nature. In reality she is a die-hard fan of anime, manga, and otaku culture.

(Source: MU)