Usami Ichika and her companions decide to participate in a renowned sweets competition in France. However, Ciel appears to be struggling with her usual self, facing difficulties in both baking and transforming into a Cure. During the event, they encounter Jean-Pierre, a pastry chef who once mentored Ciel in Paris. Inspired, Ichika suggests that Ciel and Jean collaborate on creating a nostalgic dessert named 'Mille-feuille' for the contest. Just as they embark on this venture, a sudden attack by a mysterious monster disrupts their plans, revealing a hidden secret about the sweetest treat in Paris. Amidst the chaos, they are left pondering the perplexing turn of events.