We herein report a case of suspected Borrelia miyamotoi disease in Hokkaido, Japan. The patient complained of lassitude, arthralgia, and high fever after a tick bite. Furthermore, at the time of consultation, the patient exhibited momentary loss of consciousness and low blood pressure. Laboratory tests revealed elevation of liver enzymes, thrombocytopenia, and increased C-reactive protein. Seroconversion to B. miyamotoi glycerophosphoryl diester phosphodiesterase antigen suggested the patient was infected with a relapsing fever group Borrelia species.