Kō Kawakami is the older brother of Sachi Kawakami, the central figure in the story. He is a high school-aged young man who lives with his family and maintains a calm, composed exterior that often masks a more intense, quietly protective nature. While he appears mature and easygoing, he can come across as harsh or cold when he feels his sister is in a vulnerable position. His primary motivation is to safeguard Sachi as she navigates the overwhelming reality of an unplanned pregnancy, and he acts as a stabilizing presence within the household. Rather than offering overt emotional comfort, Kō tends to provide practical observations or blunt remarks that cut through tension, sometimes serving as a catalyst for the family to address difficult truths. He interacts with his parents in a straightforward, sometimes distant manner, and his relationship with Sachi is defined by a deep though understated loyalty. As the story unfolds, Kō develops from a seemingly detached observer into someone who more openly shows his concern and willingness to support his sister, even when his methods are unorthodox. His key strength lies in his ability to remain levelheaded during chaotic moments and to speak plainly when others hesitate, making him an unlikely but essential anchor in the family’s journey.