The fantastical, magical worlds of isekai anime aren't particularly known for being creepy. The medieval RPG-inspired settings that make up the overwhelming majority of isekai series tend to be more awe-inspiring and mystical than scary. Instead, its isekai's protagonists themselves that make up the unsavory side of the genre – to even become an isekai typically involves dying and being revived in a foreign body.
Source:https://www.cbr.com/creepy-isekai-protagonists/