Kou's older brother by eight years. He works as an English teacher at Futaba's high school. Futaba was initially interested in Youichi upon entering high school because he reminded her of Kou, but was unaware that the two were brothers. Youichi knows about Shuuko's crush on him but always rebuffs her advances, telling her that he will never see her as anything more than a student. However, he never hesitates to help her in times of need and is happy whenever he sees that she is fitting in. He enjoys a playful "rivalry" with Aya over Shuuko. He often gives Futaba advice whenever she feels unsure about herself or about Kou.
