Nene notes that Sumire's personality shows a great resemblance to Aoi, in which both demeanors are cheerful, helpful, and lighthearted in their interactions. However, she also has a manipulative, almost sadistic side. This is shown in Chapter 89 when Sumire takes care of wounded animals, and explains that she enjoys looking after them because she has absolute control over them. Sumire has a strong infatuation with keeping Nene and Hanako as her newfound pets, stating they reminded her of 'lost raccoons'. Because of this, she established precautions such as creating an electrifying barrier around her home to prevent escapes and putting Nene in doing housework.

In their first meeting, Sumire held a cold demeanor when it came to meeting the mountain villagers that invaded her garden. She also has an authoritative position, shown by how all of the villagers bowed to her presence. To Hanako, her identity remains suspicious as he deduces that she must be following No. 6's orders. Her memories featured her being the kannagi for sacrifice in the past, and she intended to substitute Nene as the sacrifice in hopes of getting a response from No. 6.