In the kingdom of Savanny, the first Prince William is known as the Ice Prince. Having risen to the rank of Vice-Captain of the Royal Guard through his own strength, he holds a deep distrust of women and has no interest in romance. Worried by his lack of a suitable partner, the king and queen host a gathering of eligible daughters from count-level families and above. During the event, William points to a young woman quietly eating in the corner and declares, This one will do. The chosen girl is the cheerful and somewhat absent-minded Count's daughter, Liliana Villiers, who was far more interested in the royal cuisine than in catching the prince's eye. Thus, she is suddenly thrust into the role of the prince's fiancée without her consent.

Determined to have the engagement annulled, Liliana finds herself facing an unexpected obstacle. The cold and stoic prince begins to show a completely different side, becoming increasingly doting and affectionate towards her. He feeds her by hand, lets her sit on his lap, and treats her like a small, adorable animal, much to her confusion and protest. The narrative follows their push-and-pull relationship as Liliana, who claims to prefer sweets over romance, tries to resist his advances while William gradually sheds his icy exterior.

A notable early arc involves Liliana teaming up with the third prince, Jose, who initially disapproves of his elder brother's engagement. Their plan to sabotage the relationship backfires, however, as it only serves to make William realize the depth of his feelings for Liliana. As the story progresses, the pair navigates the formalities of royal engagement, with William attempting to court Liliana on a first date. After a series of misunderstandings and failed attempts to deny their feelings, they finally confess their love for one another by the end of the second volume. Later arcs introduce rivals for affection and challenges such as jealousy, misunderstandings involving foreign princesses, and the trials of school life, all of which ultimately strengthen the bond between the small-animal-like heroine and the once-icy prince.