That Time I Got Reincarnated as a Slime: The Ways of the Monster Nation

WARNING! This spin-off follows the Light Novel and is much further ahead of the manga and anime. So if you don't want certain elements to be spoiled. Steer clear. As of April 1, 2024, this spin-off has been officially discontinued due to the author's health. It was on hiatus for 2 years before this for the same reason but now it's officially confirmed to be discontinued. This story follows a female rabbit-beastmen whose unique skill allows her to analyze things with much detail. This ability interests Rimuru who wants her to make a guidebook on the city/nation of Tempest. So much like the Slime Diaries spin-off, this isa slice-of-life style story following the shenanigans of many known characters of the series. It is very entertaining if you wish for more shenanigans of the side characters. However, timeline-wise, this story jumps around a bit where it mentions plot points that already happened and shows characters that were introduced via Light Novel and will not cover it in the spin-off itself. Again, if you don't mind spoilers or already know the gist of what's going to happen in the manga/anime, then it's worth a read.