Yamame Hattori is a cheerful and eager kunoichi of the Hattori ninja clan, loyal to her childhood friend and relative, Mamoru Kagemori. She carries shuriken at all times and is skilled in ninja techniques, often assisted by her ninja rabbit companion, Miminosuke.

One significant childhood memory involves Mamoru comforting her, leaving a lasting impression. Another incident saw Mamoru protect her from a wild bear; he was injured during the attack, resulting in his enduring fear of bears. Upon reuniting later, Yamame expressed disappointment at Mamoru's glasses-wearing appearance, perceiving him as changed. This perception shifted dramatically after Mamoru rescued her from Chin Panji, a Chinese master of Animal Style combat employed by a yakuza boss. Following this, Yamame apologized for her earlier judgment and acknowledged Mamoru's true capabilities. The next day, she transferred into his school to be closer to him.

Yamame maintains a consistently friendly, supportive, and non-romantic relationship with Mamoru. She actively encourages his romantic interest in Yuna Konnyaku. While generally bubbly, she demonstrates seriousness and focus during ninja duties. Recognized within the Hattori clan as a trusted and reliable member, her primary role involves supporting Mamoru in protection missions for his school and classmates.