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]

Scaling the Tower of Druaga is no game. Infested with slimes and dragons, very few reach the top to face Druaga, the demon protecting the treasured Blue Crystal Rod. It is a campaign undertaken by only the bravest swordsmen and wisest sorcerers—and Jil. A young, inexperienced Guardian, Jil raises his shield to play the role of hero, battling his way up to the level where Druaga waits.

[Source: Funimation]

With broken spirits and enigmatic questions that hold no answers lingering, Jil is still trying to figure everything out. Then, a mysterious girl named Kai appears before him and says: "Take me to the top of the tower."

Kai's request shrouded in ambiguity, Jil will have another chance to work towards completing his destiny and ascend the Tower. With his hopes and aspirations seemingly slipping out of his hands, Jil must rise to the challenge once again on this never-ending adventure.

[Source: Crunchyroll]