That Time I Got Reincarnated As A Slime The Movie: Tears Of The Azure Sea

Rimuru Tempest and his companions are on vacation at a private resort. Their peace is shattered by the arrival of Yura, a priestess from the undersea nation of Kaien, who seeks help to save her people. The kingdom of Kaien is being threatened by a mysterious pollution of the "Azure Sea" and a conspiracy to forcibly awaken the dormant deity. Rimuru and the Tempest executives must dive into the deep sea to uncover the plot and stop an invasion of the surface world.