That Time I Got Reincarnated as a Slime, Volume 7 (manga) — Fuse

COMMANDER IN GRIEF Milim is now a resident of Tempest, but her presence there sets off a chain of events that begins with the entrance of a rival demon lord's servants. Rimuru, as the leader of the Jura Forest Alliance, must swiftly and delicately handle this potential threat, but it won't be easy to do so while managing the behavior of an all-powerful yet child-like demon lord and leading an entire nation of monsters…