Princess Mana, daughter of Sweetsland's King and Queen, resides in the kingdom neighboring Jewel Land while preparing for her seventh birthday celebration. Her magically imbued crown collects and amplifies Sweetspets' powers, a crucial ability during the birthday events. Despite royalty, she interacts with ease and humility, enjoying manga-drawing, dancing, and cake.

A gummy object plummeting from the sky introduces Gumimin, an amnesiac Sweetspet boy, inadvertently igniting Sweetsland's crisis. Simultaneously, her father pressures her to marry Duke Crème de Brulée, the realm's young duke. She rejects this due to the Duke's concealed plot to overthrow the monarchy—a scheme involving spy deployments like Chocolat and Gumimin's memory manipulation.

After resolving the kingdom's peril—saved through confectionery consumption—she partially reconciles with her father's wishes. Choosing forgiveness, she permits the Duke's attendance at her birthday alongside Jewelpets and Sweetspets. The celebration proceeds with Ruby and Jewelpets performing a commemorative dance. Her journey balances royal duties with personal agency, culminating in inclusive reconciliation post-conflict.