Kuro Nero

Gender: Female   

Species: Anti-bird
Height: 8 cm

An Anti-bird who decided to stay alongside Asta after encountering him at the beginning of the Magic Knights Entrance Exam.

It's later revealed that she is a human, her name is Secre Swallowtail. She was the servant of Lumiere Silvamillion Clover, prince of the Clover Kingdom and the first Magic Emperor. She is transformed into an anti-bird named Nero after sealing Lumiere into a statue.