Unaired episode included in the fourth Blu-ray volume. The episode will take place during the same time in episode 16 (episode 5 in second cours) and depict what Eris and Ruijerd were up to outside the main story, as teased by the comment "Goblin Extermination."
Mushoku Tensei: Jobless Reincarnation - Eris the Goblin Slayer, 無職転生 ～異世界行ったら本気だす～ エリスのゴブリン討伐, Mushoku Tensei: Isekai Ittara Honki Dasu Special Mushoku Tensei: Jobless Reincarnation - Eris the Goblin Slayer (Dub)
