The Fantasma de Medusa first manifests in Volume 2 as a translucent, dream-laden jellyfish whose pale eyes promise lethal slumber. Across the series it evolves from a solitary oceanic predator into a recurring symbol of dream invasion, its liquid core becoming a conduit for the collective unconscious of the spirit world. Later volumes reveal that its appearance heralds incursions by higher-sequence dream-pathway entities, transforming the creature from a mere monster into an unwitting herald of the apocalypse.

The Fantasma de Medusa first manifests in Volume 2 as a translucent, dream-laden jellyfish whose pale eyes promise lethal slumber. Across the series it evolves from a solitary oceanic predator into a recurring symbol of dream invasion, its liquid core becoming a conduit for the collective unconscious of the spirit world. Later volumes reveal that its appearance heralds incursions by higher-sequence dream-pathway entities, transforming the creature from a mere monster into an unwitting herald of the apocalypse.