Miya Koshiro is a supporting character in the anime Yumeiro Pâtissière. She is the daughter of the president of Château Seika, a major Japanese confectionery company known for its sweets and chocolates. Because of her family’s wealth and influence, she is often called “Ojou” (heiress) by other students at Saint Marie Academy. She is a third-year middle school student, one year above the protagonist Ichigo Amano.

Her personality is best described as a himedere, meaning she expects to be treated like royalty. She is spoiled, obsessive, and possessive, especially when it comes to her feelings for Makoto Kashino, one of the “Sweet Princes” of the academy. Her intense crush on Kashino drives her to pursue him relentlessly, often using her father’s company resources to try to get closer to him or to create advantages for herself. This behavior is a significant factor in Kashino’s initial dislike of women. Despite her seemingly self-centered exterior, she also exhibits a supportive and confident side, and she is genuinely determined to become a skilled pastry chef. Her motivation for improving her patisserie skills is largely tied to her belief that she can win Kashino’s heart through her culinary talent.

In the story, Miya serves as a rival and occasional antagonist to Ichigo and her team. She is willing to do almost anything to get what she wants, including hiring famous pâtissiers for private training sessions. However, she is not without a sense of effort and ambition; she takes her training seriously even if her methods are over-the-top. Her direct confrontations with Ichigo in baking competitions do not result in victories for her, despite her use of premium ingredients. She works alongside the sweets spirit Marron, a chestnut-themed spirit, and together they form a capable team.

Her key relationship is with Makoto Kashino, whom she obsesses over. This one-sided affection defines much of her behavior. She also interacts with Ichigo as a rival, and with her two attendants, Satou and Shioya, who are often seen accompanying her. Development-wise, Miya remains largely consistent throughout the series, maintaining her spoiled and determined nature, though she occasionally shows moments of genuine support for others’ efforts. Her notable abilities lie in her knowledge of high-quality ingredients and her access to resources, though her personal baking skill is competent but not exceptional compared to the main protagonists.