Mahiro Muto  

, 武藤 まひろ

Mahiro is Kazukis younger sister, currently in her first year at his school. Known for being carefree and bubbly, she sometimes appears to lack practicality and doesn't seem concerned about certain actions like lending her brother her gym clothes from school. Her character traits closely resemble those of her older brother, leading many people to believe they are siblings despite their physical differences. Mahiro secretly hopes that Kazuki and Tokiko will marry so she can become her new sister.