Druaga no Tou: The Aegis of Uruk - Jil no Bouken
English title: Tower of Druaga: The Aegis of Uruk - Jil's Adventure
Japanese title: ドルアーガの塔 〜the Aegis of URUK〜 「ジルの冒険」
Alternative titles: Tower of Druaga: The Aegis of Uruk Alternate First Episode, Tower of Druaga: The Aegis of Uruk Special
Type: Special
Source: Game
Episodes: 1
Status: Finished Airing
Aired: Apr 4, 2008
Duration: 24 min
Rating: PG-13 - Teens 13 or older
Studios: Gonzo
Licensors: Funimation
Genres: Adventure, Fantasy

This is a special "back-side" (ura) episode aired on GyaO simultaneously with original broadcast which features the background story from party's side instead of Jil's. 

(Source: AniDB)