Aguri Madoka, known as Cure Ace, originates from the Trump Kingdom as the purified half of Princess Marie Ange's divided heart. This division occurred when the princess separated her capacity for love and protection from darker emotions as her father succumbed to evil. Sent to Earth, she was discovered and adopted by Madoka Mari, growing into a composed and wise individual despite her youth. Her personality blends seriousness, a strict adherence to rules, and a strong sense of duty, sometimes leading to unintentional harshness. She possesses a deep appreciation for sweets and fine food, expressing delight with refined phrases like "Bravo." Relationships shape her: she protects schoolmate Eru Morimoto from bullies and shares a complex bond with Regina, who embodies the princess's darker half. Their dynamic evolves from rivalry into collaboration to save their father, the Trump King. Her connection to the fairy baby Ai is significant, with Ai seeing her as an older sister and enabling her transformation into Cure Ace.

As Cure Ace, Aguri wields advanced magical abilities, initially constrained by a five-minute time limit due to her fragmented history. She overcomes this limitation after regaining full memories via the Eternal Golden Crown. Her transformation employs the Love Eyes Palette and a Lovead generated by Ai, physically aging her to a mature form. Her primary weapon, the Love Kiss Rouge, enables the "Ace Shot" attack; effects vary by lipstick hue—red purifies, purple immobilizes, yellow entangles, and blue contains. A secondary attack, "Ace Mirror Flash," uses the Magical Lovely Pad. She accesses a powered-up state marked by a red aura in intense battles. In the film *Eiga Dokidoki! Precure Mana Kekkon!!? Mirai ni Tsunagu Kibō no Dress*, Cure Ace appears during the climax to aid Cure Sword against Marsh's henchmen. Her inclusion in the wedding scene reflects her late series introduction and subtly reinforces her role as a protector of others' futures and memories.

Her journey extends beyond the main series into an epilogue where she prevents a satellite crash and temporarily assumes the form of Cure Joker alongside Regina to face new threats. This collaboration strengthens their sisterly bond and culminates in a meeting with Princess Marie Ange's spirit, resolving their shared legacy. The name "Aguri Madoka" carries symbolic weight: "Madoka" can mean "circle" or "yen," while "Aguri" historically signifies a daughter intended as her parents' last female child. An anagram of her name, "En Agri," rearranges to "Regina," hinting at their intertwined destinies.