Shuffle! Prologue
Japanese title: SHUFFLE! (シャッフル!) Prologue
Type: OVA
Source: Visual novel
Episodes: 1
Status: Finished Airing
Aired: May 27, 2005
Duration: 8 min
Rating: PG-13 - Teens 13 or older
Studios: asread.
Producers: Lantis
Genres: Comedy, Fantasy, Romance
Themes: Harem, School, Urban Fantasy

Shuffle! Prologue is a short OVA teaser for the Shuffle! anime series based on the visual novel of the same name. While some of the animation was reused for the first episode of the anime series, most of Shuffle! Prologue is unique animation not repeated in the series, although the story itself is retold. 

(Source: Wikipedia)