Miyuki is a bright, kind-hearted, and energetic girl who loves fairytales. She is always happy and optimistic but seems occasionally naive. Miyuki is also really clumsy to the point where she sometimes ends up hurting herself when she gets overly excited, such as hitting her head after falling back. Multiple running gags in the series include Miyuki falling flat on her face after she randomly trips and her always getting hit in the face by random objects such as Candy and Pop's storybook.

During her childhood, Miyuki was a quiet and timid girl who was too afraid to interact with others. She would often read storybooks to console herself until Tae, her grandmother, gave her a mirror necklace and told her to always put a smile on her face in front of it. An encounter with a mysterious girl results in her becoming who she is now. Despite being normally cheerful, she still shows notable signs of nervousness such as her class introduction, being on stage for the fashion concert, and finding the Akanbe frightening in her first battle. However, Miyuki gains confidence in her abilities and develops courage over time. Her enthusiasm, motivation, and determination often help her to lead the other Cures in battle.

As she loves fairytales, her favorite childhood is reading storybooks. Miyuki loves them because the happy endings to these stories always leave a warm and happy feeling inside her heart, which she summarizes as a feeling of being "ultra happy!", making her cherish happiness and smiles in high regard. She hates seeing others being sad or crying and does her best to cheer them up when they do. Miyuki eventually realizes what her own happiness is and wishes to share that kindness and feeling with others.