Gioconda is a noble from the kingdom of Ruvinagald, holding the title of a very influential marquess. She serves as a primary antagonist in the narrative, a figure of authority whose ambitions and cruelty drive much of the central conflict. Her past is marked by a pivotal act of profound selfishness. When the kingdom of Taforashia was devastated by a deadly plague known as the Durum sickness, several surrounding nations, including Ruvinagald, assembled relief aid. Gioconda, however, embezzled these supplies, funds that were a lifeline for the dying nation, and effectively ensured its collapse.

Her personality is defined by corruption, ambition, and a complete lack of remorse. She rationalizes her theft of Taforashia's aid by claiming the doomed nation would have wasted the resources, showing a callous dismissal of the suffering she caused. Beyond her political crimes, Gioconda harbors a personal penchant for violence. She constructed an underground coliseum beneath her castle for her own entertainment, where she would duel her own husbands. This pastime resulted in the deaths of all four of them, demonstrating not only her cruelty but also her formidable personal combat skills.

In the present of the story, Gioconda's primary motivation is obtaining the Sword of Light, a powerful artifact in the possession of Pokota, a prince of the ruined Taforashia. To achieve this and consolidate her power, she commands a network of powerful operatives. These include Ozel, a doll possessing its own will, and the deadly assassin Zuma. She also forms a strategic alliance with Duclis, a beastman seeking revenge for the fall of Taforashia. She and Duclis work together on experiments involving the Zanaffar, a powerful and dangerous magical armor from Taforashia. Gioconda creates copies of this armor, wearing one herself and providing another to Duclis, in pursuit of military power and profit, even selling incomplete versions known as magic tanks.

Her role in the story places her directly in opposition to the main protagonists, including Lina Inverse and Gourry Gabriev. During a confrontation in an arena, Gioconda engages Gourry in a sword fight. Despite Gourry's renowned swordsmanship, Gioconda proves to be a highly skilled duelist, holding her own and even flippantly offering him the chance to become her fifth husband. Ultimately, her web of schemes collapses when Duclis discovers her betrayal in stealing Taforashia's relief aid. In his rage, he strikes her, but the blow activates the perfected Zanaffar armor she wears beneath her dress. The armor, created from a fragment of the Claire Bible manuscript, was too powerful to be safely controlled, and instead of granting her power, it consumes her, releasing the demon beast Zanaffar and causing Gioconda to meet her end. Gioconda is a formidable physical combatant, as shown when she matches Gourry, and is a skilled swordswoman in her own right. She also has considerable resources and political influence as a marquess, which she uses to orchestrate illegal activities and command powerful subordinates. However, her most notable ability is her ruthless cunning, which ultimately proves to be her downfall as it leads to the betrayal that unleashes the uncontrollable power of her own armor.