Using all his skills, Soei-one of Rimuru's oldest and most faithful companions-must fight the assassin who brought a sniper rifle to a fantasy world! Then, when the smoke of battle clears, Rimuru and his friends join an expedition to the lost city of Amirita, a mysterious ruin full of treasure and danger. But in the darkness of the lost city, evil forces wait for the chance to strike. Weakened by the deadly dungeon, the slime finally comes face to face with Maribel, the mind-controlling child whose masterplan is Rimuru's destruction!