Amaryllis is regarded as the most beautiful resident of Treasure Island, a slim young woman with wavy, shoulder-length black hair and large, expressive eyes. She typically wears a long cream-colored dress with a shell-like bra and platform shoes adorned with clams and pearls. At first glance she appears coquettish and charming, but beneath that demeanor she is abrasive, short-tempered, and highly manipulative, using her looks to distract men and gain favors. Her motives are largely altruistic: she deeply disapproves of the petrification practices enforced by the island’s rulers, having witnessed friends turned to stone for minor infractions. At age twelve, she and four friends broke island rules by sailing offshore; the warrior Kirisame used a grenade-like device emitting green light that petrified her companions, and Amaryllis narrowly escaped by tearing off the section of her hair where the light grazed her. This convinced her that petrification functioned as a weapon, and she deliberately cultivated her beauty to gain entry into the Master’s inner palace, intending to steal the device and end the tyranny. She encounters Senku Ishigami and his crew during their reconnaissance, sharing her backstory and objective to aid strategic planning. Collaborating with the Kingdom of Science, she helps infiltrate the Master’s selection for the inner palace, using her cosmetic expertise to disguise Kohaku and suggesting multiple candidates, which results in Ginro’s reluctant crossdressing participation. During the mission she maintains composure when Minister Ibara attempts to assault Kohaku, an incident halted by Mozu, and later witnesses Ibara petrifying Kohaku and Ginro, memorizing critical details to report to Senku. Amaryllis proves quick-thinking and resourceful, escaping petrification once by tearing her hair and swimming to safety. She forms a strong friendship with Kohaku and respects Senku’s intellect and immunity to her charms. Later she remains on Treasure Island to assist in building a rocket launch pad, demonstrating her continued commitment to the Kingdom of Science’s long-term goals.