Do you know that 30% of primary school students and 65% of high school students have myopia in Japan? Also, do you know that progressive myopia leads to blindness? Now, children with myopia are rapidly increasing all over the world. It is at a level where you would want to declare it as pandemic. However, the real cause is unknown. Here, I present you with the breakthrough method to prevent and halt myopia which may overturn the prevailing theory that "myopia cannot be prevented." ---Expert taken from the chapter「Introduction」--- Do you sense, as I do, that myopia is increasing among children? There seems to be a general uneasiness among parents who suspect that their children in the community are increasingly nearsighted. Suddenly, it seems everybody is nearsighted. This uptick in nearsightedness is not just a localized phenomenon. In recent years, the entire world has seen a rise in myopia. The 2013 School Health Statistics Survey by MEXT (the Japan Ministry of Education, Culture, Sports, Science, and Technology) revealed that primary school students with uncorrected visual acuity (VA) of 0.3 or less had more than tripled since 1979. Moreover, the percentage of those with unaided vision of less than 0.3 rises with age (33% in 2013); the data showed that 65% of high school students had naked-eye vision of less than 1.0. Of all the theories proposed to date, the only one bearing truth is that outdoor play helps suppress myopia. Although longer periods of outdoor activity seem preferable, researchers disagree on the required duration, suggestions range from 1 hour per day to 14 hours per week. As nobody knows why playing outdoor helps prevent myopia and its mechanism remains unknown, it is impossible to set guidelines on duration.