A high school student, working as the main assistant of Mikami. He is totally enthralled by Mikami, and often tells himself that he only keeps his dangerous job because he loves Mikami. His official wages per hour is 50 yen, later increases to 51 yen early in the manga. The plots often feature his possession. He appears at first to have dormant spiritual abilities and later on in the manga, with the help of Shoryuki, a dragon princess, Yokoshima does gain various spiritual abilities of his own. His most useful technique is using his spiritual energy to create special pearls, which grant various wishes to the user.
Ten years in the future, he is married to Mikami Reiko.