A manga adaptation by Yasuhiro Miyama was serialized in ASCII Media Works' Dengeki Moeoh between the October 2006 and August 2010 issues.

The story is set at Hakujō Academy, a private high school in Japan, and centers around Yūto Ayase and his classmate Haruka Nogizaka.

Yūto promises to keep his lips sealed, since Haruka's hobby is considered unworthy of her status, and the two become close friends and start spending much of their time together.

The series originally started serialization in MediaWorks' now-defunct light novel magazine Dengeki hp with the release of volume 30 on June 18, 2004.

), is performed by Kana Ueda, Mai Goto, Rina Satō, Kaori Shimizu and Mamiko Noto, the various voice actresses for the main characters of the anime collectively known as The N's.

A four-episode original video animation series titled Haruka Nogizaka's Secret: Finale[8] was released between August 29 and November 28, 2012.

A visual novel based on the series for the PlayStation 2 developed by Vridge is published by ASCII Media Works and was released on September 25, 2008 in Japan entitled Haruka Nogizaka's Secret: Cosplay Hajimemashita (乃木坂春香の秘密 こすぷれ、はじめました♥).

[9][10][11] A second video novel, also developed by Vridge and published by ASCII Media Works, is titled Haruka Nogizaka's Secret: Dōjinshi Hajimemashita (乃木坂春香の秘密 同人誌はじめました♥) and was originally released as a five-part digital download online playable on the PlayStation Portable on February 26, 2010.