That Time I Got Reincarnated as a Slime (2018)

S03E23 The Labyrinth Is Opened

The grand opening of Rimuru’s dungeon has arrived, drawing eager challengers—including his newest ally, Masayuki, who steps up among the first to test its depths. But once the festival’s cheers fade and the crowds disperse, a far greater task looms on the horizon for Rimuru, one that will demand everything he has.