An adult female of the argulid branchiuran Argulus coregoni Thorell, 1864 was collected from the body surface of a recently described, rare odontobutid Odontobutis hikimius (called “ishidonko”) in the Ishitani River, a tributary of the Hikimi River within the Takatsu River system, Shimane Prefecture, Japan. This collection represents a new host record for A. coregoni. This branchiuran is the first species of parasite found from O. hikimius.