Druaga no Tou: The Aegis of Uruk - Jil no Bouken

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)