Mushoku Tensei: Isekai Ittara Honki Dasu Special

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." (Source: MAL News)