Druaga no Tou: The Aegis of Uruk - Jil no Bouken
Tower of Druaga: The Aegis of Uruk Special
ドルアーガの塔 〜the Aegis of URUK〜 「ジルの冒険」
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)