At her best, Sumireko is just like any other highschool girl. Friendly, passionate about life. At her worst, she's a completely hubristic and stubborn girl, constantly putting herself in danger for it. Very smart, brave, bold, and hubristic. A self-proclaimed chuunibyou(of the real variety due to her powers), she also has a bit of a superiority complex. Wound up going fully yandere for you after you joined the Secret Sealing Club and becoming her first real friend. Has psychic powers.