That Time I Got Reincarnated as a Slime: Trinity in Tempest (Manga) 8

The war against Demon Lord Clayman has come to an end and Phos, Stella, and Nemu are just beginning to settle into their new routines in the now peaceful land of Tempest when they're suddenly called out on a mission to investigate the Western Nations. They are quickly joined by a seemingly innocuous cat, who is actually an incredibly powerful Demon in disguise. The three girls have barely arrived in the Human-run city of Blumund before plunging headfirst into a mess of trouble!

Volume 8 of the That Time I Got Reincarnated as a Slime: Trinity in Tempest manga series by Tae Tono.