That Time I Got Reincarnated as a Slime: The Movie - Scarlet Bond

Synopsis

In Raja, a small country located to the west of Tempest. Rimuru and his companions get involved in a long-running conspiracy that swirls around the mysterious power of the queen. Rimuru and his commander Benimaru also encounter another ogre survivor named Hiiro, a man that used to be the brother of Benimaru. (Source: ANN)