Hamaji is a young female hunter from a remote mountain region. Raised by her grandfather after her parents disappeared, she relocated to Edo following his death at the invitation of her older brother, Dousetsu. He sought her skills to hunt the supernatural fuse – half-human, half-dog entities that consume human souls.

She possesses auburn hair, brown eyes, and often rosy cheeks. Her practical attire and demeanor frequently lead others to mistake her for a young man, though she presents notably differently in formal wear like the pink kimono she adapts for mobility during crucial moments.

Overwhelmed by Edo's urban environment and hindered by illiteracy, Hamaji embodies a "Country Mouse" struggling to navigate the city. Her expertise with guns and tracking, honed in the mountains, is initially focused on aiding her brother's bounty hunt. This results in her participation in killing the fuse Itezuru, an act that inadvertently fuels further conflict.

Her moral complexity emerges through her relationship with Shino, a fuse she meets upon arriving in Edo. Despite the inherent enmity between their kinds, Hamaji forms a connection with him. Shino views her as a "Morality Pet," suppressing his instinct to consume her soul and those of others near her. This dynamic culminates when Hamaji confronts Shino during his attack on Edo's leadership, wearing the kimono he gifted her. Her intervention and plea for understanding contribute to his decision to spare the shogun and leave Edo.

Hamaji experiences significant emotional turmoil, including a "Heroic BSoD" (Breakdown State) after Itezuru's death and her final encounter with Shino. Her journey concludes with her adapting to life in Edo, receiving periodic letters from Shino, and witnessing her brother's new family life with his wife, Funamushi, and their child.