That Time I Got Reincarnated as a Slime, Volume 10 (manga) — Fuse

Over the course of his new life as a slime, Rimuru has overcome many trials and tribulations -- aggressive neighbors, treacherous plots, deadly beasts -- to build his very own nation of monsters. For a change of pace, he's decided to engage in a diplomatic tour of the nearby human kingdoms, where he might have found his most challenging adversary yet: a classroom of rowdy children! Can he live up to the memory of his long-lost friend Shizu by taking care of her former pupils?