Sumitori attends Ikai High School as a classmate of Ouri Kagami, sharing classes with Hiroshige, Mizuki, and Nozomi. He remains innocent and largely unaware of the existence of Shikabane and the supernatural conflicts involving them, oblivious to these events surrounding his peers. His background includes active participation in kendo, indicating dedication to this martial discipline. This kendo practice ties him to a former friend named Mitsuyoshi, who later became a Shikabane. No significant character development, interactions, or expanded background beyond these details occurs across the series' seasons, OVAs, or related media. His role is that of a secondary school character without further narrative exploration.