(Seiyu: Takahashi Mikako) Mahiro is Muramasa's sister-in-law. Although they are not blood-related, Mahiro, her sister Mayumi, and Muramasa are like a real family. Four years ago, Mahiro arrived home and saw Kyo beside her sister's dead body, holding a bloody sword in hand. She swore to avenge her sister and became a ninja under Tokugawa Ieyasu. In the anime, she is pregnant 11 years after the battle against Nobunaga (Benitora says to her, "You are responsible for two now.")