A 47-year man was hospitalized to our hospital because of consciousness disturbance. He had been abnormally fond of soy bean products since childhood. His plasma levels of ammonia and citrulline were elevated, and we suspected of adult-onset type II citrullinemia (CTLN2). Gene examination demonstrated abnormality in the SLC25A13 gene, confirming CTLN2. Serum levels of hepatobiliary enzymes were increased and his liver biopsy revealed nonalcoholic steatohepatitis. Although we considered that living donor liver transplantation was suitable for the treatment, unfortunately, there was no appropriate donor candidate in his family. He has received conservative treatments, showing a symptom-free course.