Sumitori attends Ikai High School as a classmate of Ouri Kagami, sharing classes with Hiroshige, Mizuki, and Nozomi. He possesses an innocent nature and remains largely oblivious to the existence of Shikabane and the conflicts surrounding the Kougon Sect.

Sumitori practices kendo. He was once friends with a classmate named Mitsuyoshi, who dropped out of school and later became a Shikabane. Before Mitsuyoshi's return as a Shikabane possessing telekinetic abilities, Sumitori shows Ouri Kagami a blog written by Mitsuyoshi. Rumors suggested Mitsuyoshi died by electrocution.

During the confrontation with the Shikabane Mitsuyoshi, Ouri Kagami calls Sumitori. Hearing Sumitori's voice through the phone momentarily pacifies Mitsuyoshi. This pause creates an opening for the Shikabane Hime Minai Ruo to defeat Mitsuyoshi.