That Time I Got Reincarnated as a Slime the Movie: Tears of the Azure Sea

Synopsis

After concluding the founding festival of the Demon Kingdom Federation Tempest, Rimuru and his companions are invited by Celestial Emperor Elmesia to visit her private resort island in the Magi Dynasty Thalion. However, their vacation is cut short by the arrival of Yura, a priestess from the undersea kingdom of Kaien.