Cer, Ber, and Rus are three demon brothers who embody the legendary Cerberus, each representing a different aspect of the underworld guardian. Tall, dark-haired, and imposing, Cer is the disciplined leader, Ber the hot-tempered protector, and Rus the thoughtful mediator. Accidentally summoned into the mortal world, they become bound to protect a noblewoman, gradually growing from reluctant guardians into fiercely loyal companions.