The Eris side story Chapter 1 is out now on Gangan Online : r/mushokutensei

DISC] Mushoku Tensei Eris Gaiden - Ch1.1 : r/manga

A new Mushoku Tensei spin-off manga series titled Mushoku no Tensei - Eris Gaiden by Okano Yuu & Higake Take based on Eris when she separated from Rudeus Start on Gangan Online

SF & Fantasy Manga – 3 Author_Rifujin na Magonote – Japanese Book Store

Mushoku Tensei Anthology: Roxy's side - chapter 1 : r/mushokutensei

Mushoku Tensei: Roxy Gets Serious Spinoff Manga Ends With 12th Volume (Updated) - News - Anime News Network

Eris Gaiden Manga Chapter 3, Mushoku Tensei Wiki

SF & Fantasy Manga – 2 Label_Gangan Comics UP! – Japanese Book Store

SF & Fantasy Manga – 2 Label_Gangan Comics UP! – Page 2 – Japanese Book Store

Eris Gaiden new chapter : r/mushokutensei

manga the week of - Manga Bookshelf

ComicBookAndAnimeNews@ ANIME AND MANGA WEEKEND NEWS FOR 11/12-14/21 PART 2: DRAGON BALL, BARUTO, MY HERO, ONE PIECE, FUNIMATION, AND MORE