Yokomizo was a renowned mystery writer and a close friend of Mushitaro Oguri.

Yokomizo had curly hair that reached his nape with a slicked portion of his bangs covering his forehead. Prior to his death and during Mushitaro's visions of him, Yokomizo often wore an outfit that consisted of a mandarin collar shirt underneath a three-quarter sleeve yukata tucked into a pair of hakama.

Given that he usually appears as an apparition to Mushitaro, Yokomizo's face is shown as a dark silhouette.