Kentarou Omae is the father of Kumiko Omae, the protagonist of Sound! Euphonium The Movie - Our Promise: A Brand New Day. He is a minor but impactful character in the series, primarily defined by his role within the Omae family household. A man who wears glasses, he presents an exterior that is often seen as strict, stern, and pragmatic, especially when it comes to matters of his children's futures.

His role in the story's background is largely centered on the conflict with his elder daughter, Mamiko. For a long time, Kentarou and his wife, Akiko, placed significant expectations on Mamiko, who excelled academically. They fully supported her university education, covering her tuition and living expenses, with the hope that she would follow a traditional and successful career path. When Mamiko decides to drop out of university to pursue her own dream of becoming a hairdresser, Kentarou reacts with severe disappointment. His personality is direct and unyielding in this moment; he expresses that she should have communicated her intentions much earlier and takes the decisive step of cutting off financial support for her new education, telling her she must pay for beauty school and her own living expenses.

Despite this harsh stance, his motivations are rooted in a genuine, if sternly expressed, concern for his daughters' well-being. He is not a cruel father but a pragmatic one who believes in the consequences of choices. After his heated argument with Mamiko, which leads to her leaving the house and returning her savings account book, Kentarou privately admits to Kumiko that he remains worried about her. This confession reveals that his strictness is not indifference but a conflicted form of care, showcasing a father struggling to balance his principles with his affection.

His relationship with his younger daughter, Kumiko, stands in contrast to his dynamic with Mamiko. With Kumiko, Kentarou adopts a more hands-off and permissive approach, allowing her significant freedom to make her own choices regarding school and her future. This difference in parenting style creates a point of tension within the family and is interpreted differently by the two sisters. Kumiko perceives her parents' lack of pressure as a sign that they have given up on her due to her average grades. Conversely, Mamiko feels that their parents listen to and indulge Kumiko too much, granting her a freedom she herself was never allowed. Through this conflict, the movie explores themes of parental expectations, sibling rivalry for approval, and the different ways love and concern can be expressed within a family. Kentarou's development is subtle but significant, as the narrative shows his initial, rigid disappointment softening into a quieter, more persistent worry for his eldest daughter, even if he does not openly change his stance.