That Time I Got Reincarnated as a Slime will return for Season 4 this April 3, with a new key visual and promotional video released ahead of the upcoming season. Eir Aoi’s new song “Unrealistic” was selected as the series’ opening theme, accompanied by the ending theme “Katsubou” by CiON.
That Time I Got Reincarnated as a Slime follows Satoru Mikami, an ordinary office worker who is reincarnated into a fantasy world as a slime named Rimuru. Using his newfound abilities, Rimuru and his allies set out to make the world a place where all races can co-exist in peace.
The series began life as a novel by author Fuse, which was later adapted into a manga and anime series. The anime adaptation first premiered in October 2018, followed by a second season in 2021, and a third in 2024. It has also inspired two theatrical films, with the first releasing in 2022, and the second currently airing in Japanese theatres.
Fans of Eir Aoi in particular can look forward to a new CD release coming this April 22, 2026, which will include “Unrealistic”, as well as her new track “MONSTER,” the opening theme for Classroom of the Elite Season 4.
