Magical Girl Lyrical Nanoha (魔法少女リリカルなのは, Mahou Shoujo Lyrical Nanoha) is a thirteen episode anime directed by Akiyuki Shinbo that aired between October and December of 2004, and the first installment of the Lyrical Nanoha franchise.
The series is a spin-off of the Triangle Heart series of games and OVAs.
A sequel, Magical Girl Lyrical Nanoha A's, aired between October and December of 2005. A third series, titled Magical Girl Lyrical Nanoha StrikerS began airing on April 1, 2007. Two manga sequels, Magical Girl Lyrical Nanoha ViVid and Magical Chronicle Lyrical Nanoha Force, had their first chapters published in May 2009.
This tag implicates lyrical_nanoha.