We herein report the case of a 14-year-old girl who had been experiencing chronic fatigue, febricula, and social withdrawal for 20 months. No notable abnormalities were identified during routine checkups at a general pediatric hospital; symptomatic treatments did not affect her condition. She was diagnosed with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Based on the concepts of Japanese traditional medicine, she was administered shosaikoto-based treatment. After several weeks of treatment, all of the symptoms had been dramatically alleviated, consequently resolving the issue of non-attendance at school. Shosaikoto-based medication may be a therapeutic option for treating ME/CFS in patients presenting with chronic febricula.