Ultima Testarossa is one of the Primordial Demons in the anime and light novel series 'Tensei Shitara Slime Datta Ken' (That Time I Got Reincarnated as a Slime). She is known for her cunning intelligence and sadistic tendencies, making her a formidable presence. Ultima becomes one of Rimuru Tempest's most loyal subordinates after being named, serving as one of the 'Demoness Secretaries.' Her role involves managing critical operations and eliminating threats to Tempest, often working alongside her peerless demon sisters, Carrera and Testarossa.