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.