Nogizaka Haruka no Himitsu

is a Japanese light novel series by Yusaku Igarashi, with illustrations by Shaa. The series originally started serialization in MediaWorks' now-defunct light novel magazine Dengeki hp on June 18, 2004. The first novel was released in October 2004, and is published by ASCII Media Works under their Dengeki Bunko imprint.

Synopsis
Hakujo Academy is a private high school with a student body filled with elite students. At the top of this list is the beautiful Haruka Nogizaka, an intelligent and wealthy girl who comes from a prestigious family, and is by far the most idolized girl at school. Her popularity is so great that her classmates occasionally give her French nicknames to further express their infatuation.

Yuuto Ayase is a timid boy who has the unbelievable luck of sitting in class with Haruka every day. Like many others, he admires her from a distance, never even dreaming of approaching her. But with a sudden twist of fate, Yuuto's random visit to the school library brings Haruka's darkest secret to light, one which could potentially destroy her current reputation of elegance. As it turns out, the school's most beloved princess is actually a huge otaku. This revelation marks the beginning of a beautiful friendship between these two classmates.

Nogizaka Haruka no Himitsu
An anime adaptation of the light novel aired for 12 episodes between July 3, 2008 and September 25, 2008

Nogizaka Haruka no Himitsu: Purezza
A second season of the anime that adapted the light novel aired for 12 episodes between October 6, 2009 and December 22, 2009

Nogizaka Haruka no Himitsu: Finale
The final season of the anime. Aired for 4 episodes between August 19, 2012 and November 28, 2012.

Volume 1
List of Episodes that adapted the first volume of the light novel.

Volume 2
List of Episodes that adapted the second volume of the light novel.

Volume 4
List of Episodes that adapted the fourth volume of the light novel.

Volume 3
List of Episodes that adapted the third volume of the light novel.

Volume 6
List of Episodes that adapted the sixth volume of the light novel.

Volume 5
List of Episodes that adapted the fifth volume of the light novel.

Volume 7
List of Episodes that adapted the seventh volume of the light novel.

Volume 9
List of Episodes that adapted the ninth volume of the light novel.

Anime Original Episodes (Purezza)
List of Anime Orignal Episodes in Nogizaka Haruka no Himitsu: Purezza.

Anime Original Episodes (Finale)
List of Anime Orignal Episodes in Nogizaka Haruka no Himitsu: Finale.