That Time I Got Reincarnated as a Slime: Season 1, Episode 21 - ProjectFreeTV

1 - 21: Shizu-san's Students

Rimuru becomes the new teacher for Shizu's students. However, having been summoned into this world against their will and facing shortened lifespans as a result, the children's feelings are complicated, and they're reluctant to accept Rimuru. So Rimuru proposes a series of mock battles with each of them to ascertain their abilities and allow them to let off steam.