Gene therapy is defined as “the administration of a gene or cells with introduced genes into the human body to treat diseases”, according to the Ministry of Education, Culture, Sports, Science and Technology and the Ministry of Health, Labor and Welfare in Japan. Gene therapy research is progressing globally. In Japan, clinical studies have already been conducted for some diseases. The age of gene therapy is about to begin. In our research, we have found a unique gene therapy technique that is expected to have great therapeutic effects: an innovative approach using the highly safe adeno-associated virus (AAV) as a vector to carry therapeutic genes. Based on extensive research, we are convinced that we can provide world-leading gene therapies for refractory diseases for which effective therapies have not been established yet. Primarily focusing on Parkinson’s disease, amyotrophic lateral sclerosis (ALS), and Alzheimer’s disease, we established the Gene Therapy Research Institution Co., Ltd. (GTRI) to realize this innovative research in practice, in the fastest way from basic research to clinical studies with the goal of popularizing gene therapy. Our gene therapy approaches are expected to have long-term effects via single administration; therefore, we believe that they will reduce medical expenses in our super-aged society and ensure their global competitiveness against other approaches. GTRI aims to be the world-leading gene therapy provider based in Japan and makes every effort to pursue safer virus vectors and more effective transgene technology. Our mission is to use globally available knowledge and technology for practical applications and specifically to provide these therapies to patients suffering from refractory diseases worldwide.