Nega, an alien entity from Feather Star manifesting as a cat, partners with Posi to supervise Yū Morisawa’s use of magic bestowed by Pino Pino. His name mirrors his cynical, sharp-tongued nature, opposing Posi’s optimism. Charged with guiding Yū, he imparts her initial transformation spell but deliberately limits advanced magic to deter exploitation—a rule Yū circumvents at times, tricking him into sharing spells like crafting a truth-revealing academic pen.

Brash and sardonic, Nega offsets Posi’s cheerfulness with biting remarks and lazy indifference, yet conceals genuine concern for Yū. This care surfaces when he tearfully resists separating from her, and when he shields her secret identity, such as confronting Toshio Ōtomo’s discovery of her powers—a crisis temporarily resolved via Pino Pino’s memory-altering pact.

His loyalty emerges through misidentifying another girl as Yū due to emotional ties, while episodic arcs dissect his reluctant mentorship and buried compassion. The finale underscores his evolution: once purely caustic, he gradually unveils vulnerability, cementing his growth into a guardian whose stern exterior masks deepening bonds with those he guides.