Nero-Queen is a powerful demon and one of the main antagonists in Happy Lucky Bikkuriman. She originates from the demon world known as Nero Puro, a dark realm populated by demons who seek to conquer the Earth. As a witch, she possesses a variety of magical abilities, most notably the power to transform ordinary people into monsters using special Nero Puro stickers. However, her creations are consistently thwarted by the White Puro stickers wielded by the angel Juujika.

Personality-wise, Nero-Queen is characterized by a fiery temper and an impulsive nature that often leads her into reckless situations. She is ruthless, cunning, and highly ambitious, driven by a desire for control and conquest. Despite these villainous traits, she also displays a softer side that emerges over the course of the series. She is fiercely loyal to her fellow demon allies, such as Bel, and values their camaraderie. A notable aspect of her character is her deep envy of Juujika's beauty, which fuels much of her antagonism toward the angel. She also harbors a strong dislike for Himiko.

Nero-Queen's role in the story is that of a recurring obstacle for the heroes, using her magic to create chaos and destruction in pursuit of world domination. Her key relationships include her rivalry with Juujika, her alliance with other demons, and a transformative encounter with Saint Phoenix. When she meets Saint Phoenix, she falls in love with him, and this emotional shift causes her heart to change, marking a significant development in her character arc. Ultimately, despite her formidable efforts, she is defeated by the heroes and forced to retreat to the demon world. Her abilities include strategic thinking, magical combat, and the power to afflict others with her sticker-based transformations.