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

There is a small country to the west of Tempest called Raja. As Rimuru and his companions investigate the mysterious power of the queen, they become involved in a long-running conspiracy. During their journey, Rimuru and Benimaru meet another survivor of the ogre species, an old brother of Benimaru named Hiiro. What on earth happened to Hiiro? And what experience did he have with Benimaru...