Gosick is a Japanese light novel series by Kazuki Sakuraba, published by Fujimi Shobo. Set in a fictional European country in 1924, a Japanese exchange student meets a mysterious, brilliant girl who only leaves the library to sleep. Her brother, a detective, relies on her exceptional mind to solve difficult mysteries. Tokyopop released the first novel in the series in English in April 2008 and the second in March 2010. The series has been published in Germany by Tokyopop since November 2006. A manga adaptation started serialization in the shōnen manga magazine Monthly Dragon Age on December 9, 2007. An anime adaptation by Bones premiered on January 7, 2011. Crunchyroll simulcasted the animation during its Japanese broadcast and continues to webcast it. At Otakon 2011 Bandai Entertainment announced that they would release the series in North America. In January 2012 Bandai Entertainment announced that they will withdraw from the North American market, and GOSICK's North American release was cancelled.

Taking place in the year 1937 on the eve of World War II, the story involves a mysterious spy training organization known as the "D Agency." The organization is established by Lieutenant Colonel Yuuki from the Imperial Japanese Army. His ideals lead him to recruit people beyond military academy graduates and personnel, while training them to become skilled agents in arts of manipulation. These agents would become a specialized team to conduct operations. One such antihero agent, under the name Jirou Gamou, goes on a harrowing mission to uncover secret documents titled "Black Notes," while battling forces from within and without his own ranks.

Taking place in the year 1937 on the eve of World War II, the story involves a mysterious spy training organization known as the "D Agency." The organization is established by Lieutenant Colonel Yuuki from the Imperial Japanese Army. His ideals lead him to recruit people beyond military academy graduates and personnel, while training them to become skilled agents in arts of manipulation. These agents would become a specialized team to conduct operations. One such antihero agent, under the name Jirou Gamou, goes on a harrowing mission to uncover secret documents titled "Black Notes," while battling forces from within and without his own ranks.