If you're looking for underrated isekai anime that really bring something unique to the table, I have a few suggestions you might enjoy:
1.
Mushoku Tensei: Jobless Reincarnation - While it's gained some popularity, it's still often overshadowed by bigger titles. The story follows a jobless and hopeless man who gets a second chance at life in a fantasy world. It's praised for its deep character development and the way it tackles themes of personal growth and redemption.
2.
The Devil is a Part-Timer! - This one flips the isekai genre on its head, featuring the Demon Lord Satan who ends up in modern-day Tokyo after being defeated in his world. Watching him navigate everyday life while working part-time at a fast-food joint is both comedic and heartwarming. The character dynamics are fun, and it plays with the concept of what it means to be "evil."
3.
Ascendance of a Bookworm - It follows a book-loving girl who is reborn in a medieval world where books are scarce. Her determination to change her new life revolves around her love of literature, which makes for an engaging and thoughtful narrative. The show gets into the importance of knowledge and innovation in a society that lacks both.
4.
Re:Creators - This one is unique because it involves characters from various fictional works coming to life and entering the real world. It's a meta-narrative that explores the relationship between creators and their creations, and the implications of bringing stories to life. It's a rare concept in isekai and worth checking out.
These titles provide a mix of humor, thought-provoking themes, and character growth that you may not find in the more mainstream isekai series.
Happy watching!