Nana Sakura (Minami Hamabe) and her mother used to live together in the old confectionery shop Kotsuki An. She and her childhood sweetheart, Tsubaki Takatsuki (Ryusei Yokohama), the heir of Kotsuki An, were first lovers. However, 15 years ago, after Tsubaki's father was stabbed to death, the police arrested Nana Sakura's mother based on the testimony of Tsubaki, who was only 6 years old at the time, and Nana Sakura was expelled from Kotsuki An. However, Nana Sakura's mother died during the investigation, and the case remains a mystery. 15 years later, Nana Sakura and Tsubaki meet again in a dessert duel. Tsubaki, who is interested in Nana Sakura's desserts, proposed to her when they first met without realizing that she was her childhood sweetheart. In order to prove her mother's innocence, Nana Sakura decided to conceal her true identity and use marriage with Tsubaki to enter Kotsuki An. But there, what awaits her is unexpected adversity.