That Time I Got Reincarnated as a Slime (2018)

S1E21 Shizu-san's Students

Rimuru takes on the role of teacher for Shizu's students, but the children are grappling with mixed emotions. Summoned to this world against their will and burdened by shortened lifespans, they are hesitant to embrace Rimuru. To break the ice and understand their capabilities better, Rimuru suggests a series of mock battles, offering the students a chance to express themselves and release some tension.