Otome no Inori (乙女の祈り; A Maiden's Prayer) is Mano Erina's major debut single. It was released on March 18, 2009 in four editions: one regular and 3 limited. Limited Edition A came with a bonus DVD, Limited Edition B came with a booklet, and Limited Edition C included an event lottery serial number card. A Single V was released on on March 25, 2009.
The single reached #5 on the Oricon charts, charted for five weeks, and sold a total of 25,228 copies. It is currently her highest selling single.
The lyrics of the song talks about the romance between Genji and Murasaki in the novel The Tales of Genji. Murasaki met an older Genji when she was a child and after they got together, spent years apart faithfully waiting for him to return. Heike Michiyo's song Murasaki Shikibu also refers to The Tales of Genji and Murasaki.