The U.S. market research firm eMarketer's Global Mobile Phone Usage Study reported in November 2016 that 4.3 billion of the world's 7.6 billion people use smartphones. And by 2020, 4.78 billion people worldwide are expected to have used a smartphone. This data is equivalent to 62.6% of the world's population. In parallel with this situation, the enormous social loss caused by Internet addiction and game addiction has become a problem in the past decade. And the medical field has been called upon to take countermeasures. In 2013, the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) of the American Psychiatric Association included diagnostic criteria for "Internet gaming disorder" as a future research topic. In 2018, the World Health Organization (WHO) proposed the diagnostic criteria for Gaming Disorder. In January 2022, the WHO announced that gaming disorder would be officially recognized as an international disease and included in ICD-11. The bottom line is that Internet gaming disorder is not just a social phenomenon, but a disease.