Isekai animes give their protagonist a rare opportunity and a second attempt at life. Some protagonists come to their new worlds as they were in their previous lives. Others are reborn in a new world, retaining all of their memories from their past lives. Isekai worlds can vary greatly. Some are fantastical, some are futuristic, and some meet in the middle for science fiction. It's not the most popular subgenre of isekai, but each sci-fi isekai brings something fun and enjoyable to the table.

To be a good Sci-Fi isekai, the show doesn't necessarily need to be about science fiction. Having science fiction elements can be a great way of adding interesting elements to the overall plot of the show. When protagonists like Cid Kagenou from The Eminence in Shadow are reincarnated into a new world, they bring a lot of technology with them, transforming their new worlds using science.