Mysterious Girlfriend X (Japanese: 謎の彼女X, Hepburn: Nazo no Kanojo Ekkusu) is a Japanese manga written and illustrated by Riichi Ueshiba. It was originally published as a one-shot story in 2004 before becoming a serialized comic in Kodansha's Monthly Afternoon magazine in 2006. The manga is licensed in North America by Vertical. An anime adaptation by Hoods Entertainment aired in Japan from April to June 2012, with an original video animation episode released in August 2012.
The series follows the relationship of Akira Tsubaki and Mikoto Urabe. Urabe is a transfer student who recently came to Tsubaki's school. After a series of strange events, Tsubaki finds himself addicted to Urabe's drool. Once she claims the addiction as love sickness, the relationship slowly progresses, focusing on the odd bond that comes out of the drool attachment.
As the story progresses, the relationship between the two deepens into genuine love. The manga strongly foreshadows that they will never break up, but rather will stay together for life.[2]
Mysterious Girlfriend X is written and illustrated by Riichi Ueshiba. A one-shot chapter was first published in Kodansha's seinen manga magazine Monthly Afternoon in 2004.[9] It was then serialized in the same magazine from March 25, 2006,[10][11] to September 25, 2014.[12] Kodansha collected its chapters in twelve tankōbon volumes, released from August 23, 2006 to November 21, 2014.[9][13]
The manga is available in English as part of a read-only/download-only subscription from Crunchyroll and Kodansha.[14] Vertical licensed the series for release in North America, and released the manga in six omnibus volumes from spring 2016[15] to summer 2017.
An anime adaptation by Hoods Entertainment aired in Japan between April 7, 2012 and June 30, 2012 and was simulcast by Crunchyroll.[35] An original video animation episode was released with the ninth volume of the manga on August 23, 2012.[32][36] The series has been licensed in North America by Sentai Filmworks and began streaming on The Anime Network and Hulu 31 days following its airdate.[37][38] Sentai Filmworks released a box-set containing the entire 13 episode TV series on Blu-ray and DVD June 11, 2013.[39] The opening theme is "Orchestra of Love" (恋のオーケストラ, Koi no Ōkesutora) by Ayako Yoshitani, whilst the ending theme is "Afterschool Promise" (放課後の約束, Hōkago no Yakusoku) by Yoshitani. An English dub was released in Australia by Hanabee Entertainment on June 5, 2013.[40]